Tire mounting apparatus

ABSTRACT

A tire mounting apparatus is constructed from a first working mechanism and a second working mechanism that are separate from each other. The first working mechanism is provided with a tire holding device for holding a tire and with a temporary tightening device for temporarily tightening nuts onto hub bolts to which the tire is mounted. The second working mechanism is provided with a final tightening device means for finally tightening the temporarily tightened nuts. The final tightening device includes two nut runners and an interval adjuster for adjusting an interval between the two nut runners.

TECHNICAL FIELD

The present invention relates to a tire mounting apparatus (device) anda tire mounting method for automatically mounting a tire onto the hubbolts of a motor vehicle. The present invention is also concerned with aworking apparatus (device) and a working method for automaticallyperforming a predetermined working operation on a workpiece.

BACKGROUND ART

Automobile assembling lines, for example, include a working process forautomatically mounting a tire, which is one type of heavy component,onto an automobile body using a robot.

A tire mounting apparatus, which is applied to a working process of thetype described above, usually has a tire gripper for gripping the tire,and a plurality of nut runners for tightening hub nuts onto the hubbolts of an automobile body.

As disclosed in Japanese Laid-Open Patent Publication No. 2000-210825, atire mounting apparatus of the type described above includes a pluralityof nut runners capable of placing as many nuts as the number of hubbolts of the motor vehicle at given circumferential intervals, a tiremounting mechanism for automatically mounting a tire onto the motorvehicle, a nut supply mechanism for supplying nuts in a verticalattitude one by one, and a nut arraying mechanism for placing the nutssupplied from the nut supply mechanism in a circular pattern atintervals corresponding to the circumferential intervals at which thenut runners are disposed in a circular pattern, and transferring thenuts to the nut runners.

DISCLOSURE OF INVENTION

In the above tire mounting apparatus, the tire gripping means forgripping the tire and the nut runners for fastening the tire to themotor vehicle are installed on a single robot.

In the above tire mounting apparatus, the tire gripping means forgripping the tire and the nut runners for fastening the tire to themotor vehicle are installed on a single robot.

Recently, it has been desired to scale down and simplify variousapparatus, as well as the above tire mounting apparatus, in theirentirety.

Recently, in view of the design of the vehicle, etc., it also has beendesired to reduce the clearance between the fenders and the tires.

The present invention has been made to meet the above demands. It is anobject of the present invention to provide a tire mounting apparatus anda tire mounting method, which are capable of efficiently performing anautomatic tire assembling operation with a simple and compactarrangement.

Another object of the present invention is to provide a workingapparatus and a working method, which are capable of efficientlyperforming a predetermined working operation with a simple and compactarrangement.

Still another object of the present invention is to provide a tiremounting apparatus and a tire mounting method, which are capable ofmounting a tire relatively simply on a motor vehicle having a smallclearance between the tire and the fender.

Yet another object of the present invention is to provide a tiremounting apparatus and a tire mounting method, which can be reduced inoverall size and cost.

The present invention is concerned with a tire mounting apparatus forautomatically mounting a tire onto the hub bolts of a motor vehicle.

The tire mounting apparatus comprises a first working mechanismincluding tire gripping means for gripping the tire and temporarytightening means for temporarily tightening nuts on the hub bolts onwhich the tire has been placed, and a second working mechanism includingfull tightening means for fully tightening the nuts that have beentemporarily tightened.

According to the present invention, the first working mechanism includesthe tire gripping means and the temporary tightening means, and thesecond working mechanism includes the full tightening means.Consequently, the first working mechanism and the second workingmechanism are effectively made smaller and simpler than if only a singleworking mechanism were to include a tire gripping means and tighteningmeans (nut runners).

Since the first working mechanism includes the temporary tighteningmeans, the actuator (e.g., a motor) thereof is much smaller and lighterthan if a tightening means were to tighten the nuts both temporarily andfully, thus easily allowing the entire first working mechanism to bemade smaller and lighter.

Furthermore, the first working mechanism and the second workingmechanism share the tire mounting operation. Therefore, a plurality ofoperation sequences can be performed concurrently, and the overall tiremounting control process can be made shorter and more efficient.

In the tire mounting apparatus, the second working mechanism shouldpreferably include a detection sensor for detecting positions of the hubbolts of the motor vehicle.

The tire mounting apparatus should preferably further comprise a bolthole detection sensor for detecting bolt holes of the tire, which isdisposed in a tire supply, and a control mechanism for processing hubbolt position information of the motor vehicle and bolt hole positioninformation of the tire, and controlling operation of the first workingmechanism.

In the tire mounting apparatus, the temporary tightening means shouldpreferably comprise a plurality of detachable nut runners, and a singlerotational drive source for rotating the nut runners in unison with eachother.

In the tire mounting apparatus, the full tightening means shouldpreferably comprise two nut runners, and an interval adjuster foradjusting an interval between the two nut runners.

The tire mounting apparatus should preferably further comprise a thirdworking mechanism for arraying the nuts in relation to the temporarytightening means.

The present invention is also concerned with a tire mounting method forautomatically mounting a tire onto the hub bolts of a motor vehicle.

The tire mounting method comprises the steps of gripping the tire andtemporarily tightening nuts on the hub bolts on which the tire has beenplaced with a first working mechanism, and fully tightening the nuts,which have been temporarily tightened by the first working mechanism,with a second working mechanism.

In the tire mounting method, the first working mechanism and the secondworking mechanism should preferably operate out of interference witheach other.

The tire mounting method should preferably further comprise the step ofdetecting positions of the hub bolts of the motor vehicle with thesecond working mechanism.

The tire mounting method should preferably further comprise the steps ofdetecting bolt holes of the tire, which is disposed in a tire supply,and controlling operation of the first working mechanism based on hubbolt position information of the motor vehicle and bolt hole positioninformation of the tire.

In the tire mounting method, preferably, the first working mechanism andthe second working mechanism are disposed in a tire mounting station,and the motor vehicle is intermittently fed such that the hub bolts fora front wheel and the hub bolts for a rear wheel are successively placedin the tire mounting station.

The present invention further is concerned with a tire mountingapparatus for automatically mounting a tire onto the hub bolts of amotor vehicle. The tire mounting apparatus comprises a first workingmechanism including tire gripping means for gripping the tire, andtemporary tightening means for temporarily tightening nuts on the hubbolts on which the tire has been placed, a second working mechanismdisposed in association with a first mounting region on a front wheelside or on a rear wheel side of the motor vehicle and including firstfull tightening means for fully tightening the nuts, which have beentemporarily tightened, and a third working mechanism disposed inassociation with a second mounting region on the rear wheel side or onthe front wheel side of the motor vehicle and including second fulltightening means for fully tightening the nuts, which have beentemporarily tightened.

According to the present invention, the first working mechanism includesthe tire gripping means and the temporary tightening means, the secondworking mechanism includes the first full tightening means, and thethird working mechanism includes the second full tightening means.Consequently, the first working mechanism, the second working mechanism,and the third working mechanism are effectively made smaller and simplerthan if only a single working mechanism were to include a tire grippingmeans and tightening means (nut runners).

Since the first working mechanism includes the temporary tighteningmeans, the actuator (e.g., a motor) thereof is much smaller and lighterthan if a tightening means were to tighten the nuts both temporarily andfully, thus easily allowing the entire first working mechanism to bemade smaller and lighter.

Furthermore, the first working mechanism, the second working mechanism,and the third working mechanism share the tire mounting operation.Therefore, a plurality of operation sequences can be performedconcurrently, and the overall tire mounting control process can be madeshorter and more efficient.

The second working mechanism should preferably include a first detectionsensor for detecting positions of the hub bolts in the first mountingregion, and the third working mechanism should preferably include asecond detection sensor for detecting positions of the hub bolts in thesecond mounting region.

The tire mounting apparatus should preferably further comprise a thirddetection sensor for detecting bolt holes of the tire, which is disposedin a tire supply, and a control mechanism for processing positioninformation from the first through third detection sensors andcontrolling operation of the first working mechanism.

The temporary tightening means should preferably comprise a plurality ofdetachable nut runners, and a single rotational drive source forrotating the nut runners in unison with each other.

Each of the first full tightening means and the second full tighteningmeans should preferably comprise two nut runners, and an intervaladjuster for adjusting an interval between the two nut runners.

The present invention also is concerned with a tire mounting method forautomatically mounting a tire onto the hub bolts of a motor vehicle.

The tire mounting method comprises the steps of gripping the tire andtemporarily tightening nuts on the hub bolts on which the tire has beenplaced with a first working mechanism, fully tightening the nuts thathave been temporarily tightened by the first working mechanism with asecond working mechanism, which is disposed in association with a firstmounting region on a front wheel side or on a rear wheel side of themotor vehicle, and fully tightening the nuts that have been temporarilytightened by the first working mechanism with a third working mechanism,which is disposed in association with a second mounting region on therear wheel side or on the front wheel side of the motor vehicle.

The first working mechanism, the second working mechanism, and the thirdworking mechanism should preferably operate out of interference witheach other.

The tire mounting method should preferably further comprise the step ofdetecting positions of the hub bolts in the first mounting region withthe second working mechanism, and detecting positions of the hub boltsin the second mounting region with the third working mechanism.

The tire mounting method should preferably further comprise the steps ofdetecting bolt holes of the tire, which is disposed in a tire supply,and controlling operation of the first working mechanism based on thepositions of the hub bolts in the first mounting region and the secondmounting region, and positions of the bolt holes of the tire.

A working apparatus according to the present invention comprises aworking unit for performing a working sequence on a workpiece, a firstworking mechanism for bearing the weight of the working unit, theworking unit being movably mounted on the first working mechanism, and asecond working mechanism for automatically operating the working unitaccording to the working sequence, the second working mechanism beingdetachably coupled to the working unit or to a portion of the firstworking mechanism.

According to the present invention, since the first working mechanismbears the weight of the working unit, when the second working mechanismactually causes the working unit to operate, the load imposed on thesecond working mechanism by the working unit is effectively reduced. Thesecond working mechanism can thus be reduced in size, thereby easilymaking the working apparatus smaller and simpler in its entirety.

When the second working mechanism is shut down for maintenance or thelike, the second working mechanism can be released from the working unitor from the first working mechanism. The operator is thus able tooperate the working unit easily while being assisted by the firstworking mechanism.

The first working mechanism should preferably comprise a balancermechanism or a multijoint robot.

The working unit should preferably include a nut runner forautomatically tightening nuts on hub bolts of a motor vehicle on which atire is mounted.

A working method according to the present invention comprises the stepsof mounting a working unit for performing a working sequence on aworkpiece on a first working mechanism for bearing the weight of theworking unit, the working unit being movably mounted on the firstworking mechanism, coupling a second working mechanism detachably to theworking unit or to a portion of the first working mechanism, andautomatically operating the working unit mounted on the first workingmechanism according to the working sequence with the second workingmechanism.

A tire mounting method according to the present invention is carried outby a tire mounting apparatus including a tire feed mechanism having apair of arms for gripping a tire, and a nut tightening mechanism fortightening a plurality of nuts respectively onto a plurality of hubbolts. The tire mounting method comprises a tire gripping step ofgripping the tire with the pair of arms, a tire positioning step ofpositioning the tire with respect to a tire mounting region of a motorvehicle with the pair of arms, and a nut tightening step of tighteningthe nuts respectively on the hub bolts with the nut tightening mechanismwhile the tire is gripped by the pair of arms, wherein the pair of armsgrip the tire at positions limited to upper and lower portions of thetire in the tire positioning step and the nut tightening step.

According to the present invention, a tire can relatively easily beinstalled on the motor vehicle, even if the clearance between the tireand the fender is small.

More specifically, when the tire is not in contact with the ground, thetire and the tire mounting region are biased by suspensions, and arepositioned lower than when the tire is in contact with the ground,because the tire is not subject to reactive forces from the ground.Therefore, the clearance between the tire mounting region (particularlyan upper portion thereof) and the fender before the tire is mounted isgreater than the clearance after the tire has been mounted and is heldin contact with the ground. According to the present invention, duringthe process of positioning the tire in the tire mounting region (tirepositioning process), and during the process of tightening nuts onto thehub bolts (nut tightening process), the positions where the pair ofgripper arms grip the tire are limited to upper and lower portions ofthe tire. When the tire is in contact with the ground, even ifclearances between the left, right, and upper portions of the tire andthe fender are small, thus making it difficult to grip the tire witheither one of the gripper arms, it is still possible to grip the tire inthe clearance, and hence the tire can be mounted on the motor vehiclerelatively easily.

The upper portion of the tire comprises a portion, which includes anuppermost region of the tire, and which has a symmetric axis representedby a hypothetical axis that extends through the center of the tire andthe uppermost region of the tire, and which corresponds to a firstcentral angle equal to an angle produced by dividing 360° by the numberof bolt holes of the tire. Further, the lower portion of the tirecomprises a portion, which includes a lowermost region of the tire, andwhich has a symmetric axis represented by the hypothetical axis, andwhich corresponds to a second central angle equal to an angle producedby dividing 360° by the number of bolt holes of the tire. The number ofbolt holes of the tire is 4 or more.

It is thus possible to establish an appropriate limited range, takinginto account the relationship between positions where the pair of armsgrip the tire and the bolt holes of the tire.

More specifically, the bolt holes generally are positioned at equalangles along a circle represented thereby. A bolt hole, which isdisposed in the uppermost position along the height of the motorvehicle, is present within a range between certain angles on the circlefrom the uppermost position on the circle. Since the angle between twoadjacent bolt holes is calculated by dividing 360° by the number of boltholes, the aforementioned certain angles have positive and negativevalues, each produced by dividing the angle between two adjacent boltholes by 2 (i.e., an angle produced by dividing 180° by the number ofbolt holes). For bringing the positions (rotational angles) of the boltholes and the hub bolts into alignment with each other, while limitingthe positions where the pair of arms grip the tire to upper and lowerportions of the tire, one of the arms is capable of gripping a portionof the tire, which includes an uppermost region of the tire, which has asymmetric axis represented by a hypothetical axis interconnecting thecenter of the tire and the uppermost region, and which corresponds to afirst central angle equal to an angle produced by dividing 360° by thenumber of bolt holes of the tire. Further, the other of the arms maygrip a portion of the tire, which includes a lowermost region of thetire, which has a symmetric axis represented by the hypothetical axis,and which corresponds to a second central angle equal to an angleproduced by dividing 360° by the number of bolt holes of the tire.Consequently, by limiting the positions where the pair of arms grip thetire to upper and lower portions of the tire, it is possible toestablish an appropriate limited range, taking into account therelationship between the positions where the pair of arms grip the tireand the bolt holes of the tire.

The tire mounting method further comprises a bolt hole positioninformation acquiring step for detecting the bolt holes of the tire andacquiring bolt hole position information, a tire positioning step forpositioning the tire in front of the tire mounting region of the motorvehicle while uppermost and lowermost regions of the tire are gripped bythe pair of arms, a hub bolt position information acquiring step fordetecting the hub bolts and acquiring hub bolt position information, arotational angle calculating step for calculating a rotational angle ofthe tire for positionally aligning the bolt holes and the hub bolts witheach other, and a tire rotating step for rotating the tire through thecalculated rotational angle, wherein the rotational angle of the tire islimited to within a value produced by dividing 180° by the number of hubbolts in the rotational angle calculating step.

After the tire has been positioned in front of the tire mounting region,therefore, rotation of the tire is minimized. The efficiency at whichthe tire is mounted can thus be increased.

A tire mounting apparatus according to the present invention comprises atire feed mechanism having a pair of arms for gripping a tire, and a nuttightening mechanism for tightening a plurality of nuts respectivelyonto a plurality of hub bolts, wherein the tire is positioned withrespect to a tire mounting region of a motor vehicle by the pair ofarms, the nuts are tightened respectively on the hub bolts with the nuttightening mechanism while the tire is gripped by the pair of arms, andthe pair of arms grip the tire at positions limited to upper and lowerportions of the tire when the tire is positioned and the nuts aretightened.

According to the present invention, a tire can relatively easily beinstalled on the motor vehicle, even if the clearance between the tireand the fender is small.

More specifically, when the tire is not in contact with the ground, thetire and the tire mounting region are biased by suspensions, and arepositioned lower than when the tire is in contact with the ground,because the tire is not subject to reactive forces from the ground.Therefore, the clearance between the tire mounting region (particularlyan upper portion thereof) and the fender before the tire is mounted isgreater than the clearance after the tire has been mounted and is heldin contact with the ground. According to the present invention, duringthe process of bringing a tire into abutment against a tire mountingregion (tire abutting process), and during the process of tighteningnuts on hub bolts (nut tightening process), the positions where the pairof gripper arms grip the tire are limited to upper and lower portions ofthe tire. When the tire is in contact with the ground, even if theclearances between left, right, and upper portions of the tire and thefender are small, thereby making it difficult to grip the tire witheither one of the gripper arms, it is still possible to grip the tire inthe clearance, and hence the tire can be mounted on the motor vehiclerelatively easily.

The upper portion of the tire comprises a portion, which includes anuppermost region of the tire and which has a symmetric axis representedby a hypothetical axis extending through the center of the tire and theuppermost region of the tire, and which corresponds to a first centralangle equal to an angle produced by dividing 360° by the number of boltholes of the tire. Further, the lower portion of the tire comprises aportion, which includes a lowermost region of the tire and which has asymmetric axis represented by the hypothetical axis, and whichcorresponds to a second central angle equal to an angle produced bydividing 360° by the number of bolt holes of the tire. The number ofbolt holes of the tire is 4 or more.

It is thus possible to establish an appropriate limited range, whiletaking into account the relationship between positions where the pair ofarms grip the tire and the bolt holes of the tire.

More specifically, the bolt holes generally are positioned at equalangles along a circle represented thereby. The bolt hole that isdisposed in the uppermost position along the height of the motor vehicleis present in a range between certain angles on the circle from theuppermost position on the circle. Since the angle between two adjacentbolt holes is calculated by dividing 360° by the number of bolt holes,the aforementioned certain angles have positive and negative values,each produced by dividing the angle between two adjacent bolt holes by 2(an angle produced by dividing 180° by the number of bolt holes). Forbringing the positions (rotational angles) of the bolt holes and the hubbolts into alignment with each other, while also limiting the positionswhere the pair of arms grip the tire to upper and lower portions of thetire, one of the arms may grip a portion of the tire, which includes anuppermost region of the tire, which has a symmetric axis represented bya hypothetical axis interconnecting the center of the tire and theuppermost region, and which corresponds to a first central angle equalto an angle produced by dividing 360° by the number of bolt holes of thetire. The other of the arms may grip a portion of the tire, whichincludes a lowermost region of the tire, which has a symmetric axisrepresented by the hypothetical axis, and which corresponds to a secondcentral angle equal to an angle produced by dividing 360° by the numberof bolt holes of the tire. Consequently, by limiting the positions wherethe pair of arms grip the tire to upper and lower portions of the tire,it is possible to establish an appropriate limited range, while takinginto account the relationship between the positions where the pair ofarms grip the tire and the bolt holes of the tire.

A tire mounting apparatus according to the present invention comprises arotational drive power generator for generating rotational drive powerfor tightening nuts, a first tightening unit including a plurality ofnut tighteners for tightening the nuts onto hub bolts, a secondtightening unit including a plurality of nut tighteners in a layoutdifferent from the first tightening unit, the second tightening unitbeing replaceable by the first tightening unit, and a rotational drivepower transmitter for transmitting rotational drive power from therotational drive power generator to the first tightening unit or to thesecond tightening unit, wherein the rotational drive power transmitterincludes an offsetting mechanism for offsetting a rotational axis alongwhich the rotational drive power is transmitted, thereby transmittingrotational drive power to the nut tighteners of the first tighteningunit and the nut tighteners of the second tightening unit.

According to the present invention, the rotational axis along whichrotational drive power for tightening the nuts is transmitted is offset.Therefore, it is possible to transmit rotational drive power to the nuttightening units (the first tightening unit and the second tighteningunit) while the nut tighteners are positioned in different layouts.Rotational drive power that is needed to tighten the nuts with the nuttightening units can thus be supplied from a single rotational drivepower generator. Stated otherwise, even though a plurality of rotationaldrive power generators are not provided, tires can be mounted onto aplurality of automobile bodies the hub bolts and bolt holes of whichhave different layouts, by replacing one of the first and second nuttightening units with the other. Accordingly, the tire mountingapparatus can be reduced in size and cost overall.

The offsetting mechanism may comprise a plurality of first shaft memberscoupled to the rotational drive power generator, a plurality of secondshaft members coupled to the nut tighteners, and a plurality ofuniversal joint mechanisms disposed on the first shaft members or thesecond shaft members and coupling the first shaft members and the secondshaft members to each other.

The first shaft members or the second shaft members have one ofprotruding portions with tapered distal ends and tubular sockets forengagement with the protruding portions, and the universal jointmechanisms include the other of the protruding portions and the tubularsockets. When the protruding portions and the tubular sockets engagewith each other, the first shaft members or the second shaft members andthe universal joint mechanisms become coupled to each other fortransmitting rotational drive power.

Therefore, even if axes of the first shaft member and the second shaftmember are offset from each other, the protruding portions and thetubular sockets engage with each other in order to transmit rotationaldrive power through the universal joint.

According to the present invention, a tire mounting method is carriedout by a first tightening unit including a plurality of nut tightenersfor tightening nuts onto hub bolts, and a second tightening unitincluding a plurality of nut tighteners in a layout different from thefirst tightening unit, the second tightening unit being replaceable bythe first tightening unit. The tire mounting method comprises arotational drive power generating step of generating rotational drivepower for tightening the nuts, and a rotational drive power transmittingstep of transmitting rotational drive power from the rotational drivepower generator to the nut tighteners of the first tightening unit orthe second tightening unit, wherein a rotational axis along which therotational drive power is transmitted is offset when at least one of thefirst tightening unit and the second tightening unit is used in therotational drive power transmitting step.

According to the present invention, the rotational axis along whichrotational drive power for tightening the nuts is transmitted is offset.Therefore, it is possible to transmit rotational drive power to the nuttightening units (the first tightening unit and the second tighteningunit) while the nut tighteners are positioned in different layouts. Therotational drive power that is needed to tighten the nuts with the nuttightening units can thus be supplied from a single rotational drivepower generator. Stated otherwise, even though a plurality of rotationaldrive power generators are not provided, tires can be mounted on aplurality of automobile bodies in which the hub bolts and bolt holeshave different layouts, by replacing one of the first and second nuttightening units with the other. Accordingly, the tire mountingapparatus can be reduced in size and cost overall.

According to the present invention, a tire mounting method is carriedout by a tire mounting apparatus including a first working mechanismhaving tire grippers and nut tighteners, and a second working mechanismfor generating rotational drive power in order to tighten nuts. The tiremounting method comprises a nut holding step of holding a plurality ofnuts on the nut tighteners of the first working mechanism, a tiregripping step of gripping a tire with the tire grippers of the firstworking mechanism, a tire positioning step of positioning the tire withrespect to a tire mounting region of a motor vehicle with the firstworking mechanism, and a nut tightening step of transmitting rotationaldrive power from the second working mechanism to the nut tighteners ofthe first working mechanism in order to tighten the nuts respectivelyonto a plurality of hub bolts of the motor vehicle while the tire isgripped by the tire grippers.

According to the present invention, the first working mechanism grips atire and tightens nuts, and the second working mechanism generatesrotational drive power for tightening the nuts, and transmits rotationaldrive power to the first working mechanism in order to tighten the nuts.Consequently, the first working mechanism and the second workingmechanism are effectively made smaller and simpler than if the tire weregripped and the nuts were tightened by only a single working mechanism.Since the tire is gripped and the nuts are tightened by a single workingmechanism (first working mechanism), the tire and the nuts are lesslikely to change their relative positions, thus making it possible toeasily identify positions where the nuts are to be tightened.

The first working mechanism places the nuts respectively in associationwith the hub bolts, and the nut tightening step is performed while thetire grippers are fixed in position. In the nut tightening process,therefore, it is possible to keep the first working mechanism in aconstant attitude, and to control the first working mechanism with ease.

A tire mounting apparatus according to the present invention comprises afirst working mechanism having tire grippers and nut tighteners, and asecond working mechanism for generating rotational drive power totighten nuts and for transmitting rotational drive power to the nuttighteners, wherein the rotational drive power is transmitted from thesecond working mechanism to the nut tighteners of the first workingmechanism in order to tighten the nuts onto hub bolts of a motor vehiclewhile a tire is gripped by the tire grippers.

According to the present invention, the first working mechanism grips atire and tightens nuts, and the second working mechanism generatesrotational drive power for tightening the nuts, and transmits rotationaldrive power to the first working mechanism in order to tighten the nuts.Consequently, the first working mechanism and the second workingmechanism are effectively made smaller and simpler than if the tire weregripped and the nuts were tightened by only a single working mechanism.Since the tire is gripped and the nuts are tightened by a single workingmechanism (first working mechanism), the tire and the nuts are lesslikely to change their relative positions, thus making it possible toeasily identify positions where the nuts are to be tightened.

The nut tighteners hold the nuts respectively on the hub bolts. When thenuts are tightened, therefore, it is possible to keep the first workingmechanism in a constant attitude, and to control the first workingmechanism with ease.

The second working mechanism may include a rotational drive powertransmitter for transmitting rotational drive power, and the nuttighteners may comprise, respectively in association with the hub bolts,rods that are rotatable in engagement with the rotational drive powertransmitter, bearings by which the rods are rotatably supported,wrenches that are rotatable with the rods and movable in an axialdirection of the rods in order to tighten the nuts onto the hub bolts,and biasing means disposed between the rods and the wrenches for biasingthe wrenches so as to move toward the hub bolts. Thus, it is easy totighten the nuts with the nut tighteners, while the tire is fixed inposition by the tire grippers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an assembly line incorporating a tiremounting apparatus according to a first embodiment of the presentinvention;

FIG. 2 is a perspective view of a main portion of a first workingmechanism of the tire mounting apparatus according to the firstembodiment;

FIG. 3 is a front elevational view of the main portion of the firstworking mechanism according to the first embodiment;

FIG. 4 is a side elevational view of the main portion of the firstworking mechanism according to the first embodiment;

FIG. 5 is a perspective view of a main portion of a second workingmechanism of the tire mounting apparatus according to the firstembodiment;

FIG. 6 is a block diagram of the tire mounting apparatus according tothe first embodiment;

FIG. 7 is a flowchart of an operation sequence of the first workingmechanism in a mounting method according to the first embodiment;

FIG. 8 is a flowchart of an operation sequence of the second workingmechanism in the mounting method according to the first embodiment;

FIG. 9 is a timing chart of the mounting method according to the firstembodiment;

FIG. 10 is a perspective view of an assembly line incorporating a tiremounting apparatus according to a second embodiment of the presentinvention;

FIG. 11 is a perspective view of a main portion of a first workingmechanism of the tire mounting apparatus according to the secondembodiment;

FIG. 12 is a front elevational view of the main portion of the firstworking mechanism according to the second embodiment;

FIG. 13 is a side elevational view of the main portion of the firstworking mechanism according to the second embodiment;

FIG. 14 is a perspective view of a main portion of a second workingmechanism and a third working mechanism of the tire mounting apparatusaccording to the second embodiment;

FIG. 15 is a block diagram of the tire mounting apparatus according tothe second embodiment;

FIG. 16 is a flowchart of an operation sequence of the first workingmechanism in a mounting method according to the second embodiment;

FIG. 17 is a flowchart of an operation sequence of the second workingmechanism in the mounting method according to the second embodiment;

FIG. 18 is a flowchart of an operation sequence of the third workingmechanism in the mounting method according to the second embodiment;

FIG. 19 is a timing chart of the mounting method according to the secondembodiment;

FIG. 20 is a perspective view of an assembly line incorporating a tiremounting apparatus according to a third embodiment of the presentinvention;

FIG. 21 is a front elevational view of a nut runner unit of the tiremounting apparatus according to the third embodiment;

FIG. 22 is a block diagram of the tire mounting apparatus according tothe third embodiment;

FIG. 23 is a flowchart of an operation sequence of a tire setting robotin a mounting method according to the third embodiment;

FIG. 24 is a flowchart of an operation sequence of a nut tighteningrobot in the mounting method according to the third embodiment;

FIG. 25 is a timing chart of the mounting method according to the thirdembodiment;

FIG. 26 is a block diagram of an assembly line incorporating a tiremounting apparatus according to a fourth embodiment of the presentinvention;

FIG. 27 is a perspective view of an assembly line incorporating a tiremounting apparatus according to a fifth embodiment of the presentinvention;

FIG. 28 is a perspective view of an assembly line incorporating a tiremounting apparatus according to a sixth embodiment of the presentinvention;

FIG. 29 is a perspective view showing the manner in which a tire ismounted by the tire mounting apparatus according to the sixthembodiment;

FIG. 30 is a perspective view of a main portion of a first workingmechanism of the tire mounting apparatus according to the sixthembodiment;

FIG. 31 is a front elevational view of the first working mechanismaccording to the sixth embodiment;

FIG. 32 is a perspective view of a main portion of a second workingmechanism of the tire mounting apparatus according to the sixthembodiment;

FIG. 33 is a cross-sectional view of a main portion of a rotationaldrive power transmitter of the second working mechanism according to thesixth embodiment;

FIG. 34 is a cross-sectional view showing, by way of example, a mannerin which the rotational drive power transmitter according to the sixthembodiment operates;

FIG. 35 is a view, partially in cross section, of a nut tightening unitof the first working mechanism and the rotational drive powertransmitter according to the sixth embodiment;

FIG. 36 is a front elevational view of a main portion of a lockmechanism and the nut tightening unit of the first working mechanismaccording to the sixth embodiment;

FIG. 37A is a front elevational view of the lock mechanism according tothe sixth embodiment when the lock mechanism is not fixing the nuttightening unit;

FIG. 37B is a front elevational view of the lock mechanism according tothe sixth embodiment when the lock mechanism fixes the nut tighteningunit;

FIG. 38 is a perspective view of a stand for the nut tightening unit ofthe tire mounting apparatus according to the sixth embodiment;

FIG. 39 is a front elevational view showing the manner in which the nuttightening unit is replaced using the stand for the nut tightening unitaccording to the sixth embodiment;

FIG. 40 is a block diagram of a control system of the tire mountingapparatus according to the sixth embodiment;

FIG. 41 is a flowchart of an operation sequence primarily of the firstworking mechanism according to the sixth embodiment;

FIG. 42 is a flowchart of an operation sequence primarily of the secondworking mechanism according to the sixth embodiment;

FIG. 43 is a timing chart of a process in which the tire mountingapparatus according to the sixth embodiment mounts a tire on anautomobile body; and

FIG. 44 is a view showing a positional relationship between a grippingarm of the first working mechanism according to the first embodiment, atire, and a fender.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a perspective view of an assembly line 12 incorporating a tiremounting apparatus 10 according to a first embodiment of the presentinvention.

The assembly line 12 has a feed path 16 for pitch-feeding an automobilebody (motor vehicle) 14 placed on a carriage 16 a to a tire mountingposition. A pair of tire mounting apparatus 10 (only one of which isshown in FIG. 1), disposed one on each side of the feed path 16,automatically mount tires W onto hub bolts 18 of the automobile body 14.

The tire mounting apparatus 10 has a first working mechanism 20 and asecond working mechanism 22, which are separate from each other andconstructed depending on the details of working operations, to bedescribed later. The feed path 16 feeds the automobile body 14intermittently so that a first mounting region 24 a on a front wheelside of the automobile body 14, and a second mounting region 24 b on arear wheel side of the automobile body 14 will successively bepositioned in a tire mounting station.

Proximate the first working mechanism 20, there are disposed a tirecharging conveyor 26 on which tires W are placed, a nut stock 30 foraccommodating nuts 28 that are tightened on the hub bolts 18, and athird working mechanism 33 for removing a certain number of (five orfour) nuts 28 from the nut stock 30 and placing the nuts 28 in an arrayon a nut table 32.

The first working mechanism 20 includes a robot body 34 having an arm36, which includes a hand 38 on a distal end with a rotatable index base40 mounted thereon.

As shown in FIGS. 2 through 4, the index base 40 supports thereon a tiregripping means 42 for gripping a tire W, and a temporary tighteningmeans 44 for temporarily tightening nuts 28 on hub bolts 18 with thetire W placed thereon.

The tire gripping means 42 has an attachment plate 46 secured to theindex base 40. As shown in FIGS. 2 and 3, a cam ring 50 is rotatablysupported on the attachment plate 46 by a plurality of guide rollers 48.A plurality of (e.g., three) radially extending guide rails 52 aremounted on the attachment plate 46 at equal angular intervals.

Slide bases 54 are movably mounted on the respective guide rails 52, andare coupled to the cam ring 50 by connecting rods 56. Tire holders 58are mounted on the slide bases 54. A cylinder 60 is swingably mounted onthe attachment plate 46, and a rod 62 coupled to the cylinder 60 isfixed to the cam ring 50.

As shown in FIG. 4, the temporary tightening means 44 comprises a singlemotor 64 fixed to the attachment plate 46. The motor 64 has a rotationaldrive shaft 64 a to which there is secured a drive gear 66 held in meshwith a gear train 68. A tool unit 70 is detachably mounted on the geartrain 68.

The tool unit 70 includes five (or four) nut runners 72, which arerotatable in unison with each other by the motor 64 through the geartrain 68 and the drive gear 66.

As shown in FIG. 1, the second working mechanism 22 includes a robotbody 74 having an arm 76, which includes a hand 78 on a distal end withan index base 80 rotatably mounted thereon. As shown in FIG. 5, on theindex base 80 there are mounted a full tightening means 82 for fullytightening nuts 28 that have been tightened temporarily on hub bolts 18in the first mounting region 24 a and the second mounting region 24 b,and CCD image-capturing cameras (hereinafter referred to simply ascameras) (detection sensors) 84, 86 for capturing images of the firstmounting region 24 a and the second mounting region 24 b in order tocheck positions of the respective hub bolts.

The full tightening means 82 comprises a first nut runner 90 coupled toa first motor 88, and a second nut runner 94 coupled to a second motor92. The first nut runner 90 and the second nut runner 94 are variable byan interval adjuster 98 coupled to a rod 96 a that extends from a pitchchanging cylinder 96. The interval adjuster 98 is angularly movableabout a support shaft 99. The first nut runner 90 and the second nutrunner 94 are capable of varying a pitch interval, depending on whetherfive or four nuts are used to fasten the tire W.

The third working mechanism 33 includes an arm that supports on a distalend thereof a nut chuck 87, which is openable and closable for removinga nut 28 accommodated in the nut stock 30 and placing the nut 28 on thenut table 32.

As shown in FIG. 6, the cameras 84, 86 of the second working mechanism22 output image information of the first mounting region 24 a and thesecond mounting region 24 b to a first image processor 100.

The first image processor 100 also is supplied with image information ofthe tire W (bolt holes of the tire W) from a camera (bolt hole detectionsensor) 102, which is disposed over the tire charging conveyor 26.

A camera 104 (not shown in FIG. 1) for capturing an image of nuts 28 tobe fed is fixedly positioned near the third working mechanism 33. Imageinformation of the nuts 28, which is captured by the camera 104, isinput to a second image processor 106.

The first image processor 100 is connected to an arithmetic unit 108.The arithmetic unit 108 calculates the relative positions of the hubbolts in the first mounting region 24 a, the hub bolts in the secondmounting region 24 b, and bolt holes of a tire W on the tire chargingconveyor 26. Then, the arithmetic unit 108 outputs the calculatedrelative positions to a main controller (control mechanism) 110. Thesecond image processor 106 is connected to the arithmetic unit 108,which processes image information of the nuts 28 captured by the camera104, and outputs the processed image information to the main controller110.

Based on the processed image information input thereto from thearithmetic unit 108, the main controller 110 controls operation of thefirst working mechanism 20, and also controls operation of the secondworking mechanism 22 and the third working mechanism 33.

Operation of the tire mounting apparatus 10 thus constructed will bedescribed in relation to a mounting method according to the firstembodiment, with reference to the flowcharts shown in FIGS. 7 and 8, andthe timing chart shown in FIG. 9.

An operation sequence of the first working mechanism 20 is shown in FIG.7, and an operation sequence of the second working mechanism 22 is shownin FIG. 8. The first working mechanism 20, the second working mechanism22, and the third working mechanism 33 operate in relation to eachother, as shown in FIG. 9.

First, an operation sequence of the first working mechanism 20 will bedescribed below. After gripping five nuts 28 arrayed on the nut table 32with five nut runners 72 of the temporary tightening means 44, the firstworking mechanism 20 grips a tire W on the tire charging conveyor 26with the tire gripping means 42 (step S1).

More specifically, as shown in FIG. 3, when the cylinder 60 is actuatedso as to project the rod 62 in the direction indicated by the arrow, thecam ring 50 fixed to the rod 62 is rotated in the direction indicated bythe arrow while being guided by the guide rollers 48. The connectingrods 56, the ends of which are coupled to the cam ring 50, move therespective slide bases 54 inwardly (toward the center) along the guiderails 52. Therefore, the outer circumferential surface of the tire W ispressed and held by the tire holders 58 mounted on the slide bases 54.

Having gripped the nuts 28 and the tire W, as the robot body 34 isturned, the first working mechanism 20 moves to a mounting readyposition (step S2). At this time, the first mounting region 24 a on thefront wheel side of the automobile body 14 is positioned in the tiremounting station.

If a front wheel corrective quantity, which is produced based on imagescaptured by the cameras 84, 86 associated with the second workingmechanism 22, is input (step S3: YES), control proceeds to step S4, inwhich the tire W is set in the first mounting region 24 a.

Control then proceeds to step S5, in which the nuts 28 are temporarilytightened on the respective hub bolts 18. More specifically, as shown inFIG. 4, the motor 64 is energized to cause the drive gear 66 and thegear train 68 to rotate the nut runners 72 of the tool unit 70 in unisonwith each other, thereby temporarily tightening the nuts 28 onto the hubbolts 18.

When the tire W has been temporarily tightened as a front wheel in thefirst mounting region 24 a, a front wheel setting completion signal isoutput (step S6). Control then proceeds to step S7, in which the robotbody 34 moves away from the first mounting region 24 a toward the nuttable 32.

The nut runners 72 of the temporary tightening means 44 grip five nuts28 arrayed on the nut table 32, after which the robot body 34 is turnedtoward the tire charging conveyor 26. The tire gripping means 42 grips atire W (step S8), and then is moved to the mounting ready position asthe robot body 34 is actuated (step S9).

While the tire gripping means 42 is being moved, the automobile body 14is intermittently fed along the feed path 16 in the direction indicatedby the arrow in FIG. 1, until the second mounting region 24 b on therear wheel side is positioned in the tire mounting station.

If a rear wheel corrective quantity, which is produced based on imagesignals from the cameras 84, 86 associated with the second workingmechanism 22, is input (step S10: YES), as described later, controlproceeds to step S11, in which a rear wheel tire W is set in the secondmounting region 24 b.

After the nuts 28 have been temporarily tightened on the hub bolts 18 inthe second mounting region 24 b by the temporary tightening means 44(step S12), a rear wheel setting completion signal is output (step S13).Thereafter, the first working mechanism 20 moves to its originalposition (step S14), whereupon the process of temporarily tightening thetire on the automobile body 14 is finished.

Next, an operation sequence of the second working mechanism 22 will bedescribed below with reference to FIG. 8.

The robot body 74 of the second working mechanism 22 is operated toposition the cameras 84, 86 in the tire mounting station. When the firstmounting region 24 a on the front wheel side of the automobile body 14is placed in the tire mounting station (step S21: YES), control proceedsto step S22, in which the cameras 84, 86 read image information of frontwheel hub bolts 18 in the first mounting region 24 a.

Images read by the cameras 84, 86 are output to the first imageprocessor 100, which calculates a corrective quantity for the hub bolts18 with respect to a reference position. The corrective quantity isoutput from the arithmetic unit 108 to the main controller 110 (stepS23).

The second working mechanism 22 moves to a position out of interferencewith the operation sequence of the first working mechanism 20 in thefirst mounting region 24 a (step S24). If a front wheel settingcompletion signal is input from the first working mechanism 20 (stepS25: YES), then control proceeds to step S26, in which the secondworking mechanism 22 moves to the tightening position (the firstmounting region 24 a).

In the first mounting region 24 a, the five nuts 28 already have beentemporarily tightened on the hub bolts 18. The first nut runner 90 andthe second nut runner 94 of the full tightening means 82 are rotated bythe first motor 88 and the second motor 92 in order to fully tighten twoof the nuts 28. Then, the first nut runner 90 and the second nut runner94 are turned a given angle, and thereafter, the first nut runner 90 andthe second nut runner 94 fully tighten another two of the temporarilytightened nuts 28. Then, after the first nut runner 90 and the secondnut runner 94 are turned further, the first nut runner 90, for example,fully tightens the remaining one of the temporarily tightened nuts 28(step S27).

After the tire W has been mounted in the first mounting region 24 a, thesecond working mechanism 22 moves out of interference (step S28). Then,the second working mechanism 22 moves to a rear wheel hub bolt detectingposition (step S29) and determines whether or not the automobile body 14has been fed a half pitch along the feed path 16 (step S30).

If it is judged that the automobile body 14 has been fed a half pitch(step S30: YES), i.e., if it is judged that the second mounting region24 b on the rear wheel side has been placed in the tire mountingstation, then control process to step S31, in which the cameras 84, 86read image information of rear wheel hub bolts 18 in the second mountingregion 24 b. Images read by the cameras 84, 86 are output to the firstimage processor 100, which calculates a corrective quantity for the hubbolts 18 in the second mounting region 24 b (step S32).

After the second working mechanism 22 has moved out of interference withthe second mounting region 24 b (step S33), control proceeds to stepS34, in which it is determined whether or not setting of the rear wheelby the first working mechanism 20 has been completed. If a rear wheelsetting completion signal is input (step S34: YES), then controlproceeds to step S35, in which the second working mechanism 22 moves tothe tightening position (the second mounting region 24 b).

The full tightening means 82 fully tightens two nuts 28, two nuts 28,and then one nut 28 upon rotation of the first nut runner 90 and thesecond nut runner 94 (step S36). Thereafter, control proceeds to stepS37, in which the second working mechanism 22 moves out of interference.

Using the nut chuck 87, the third working mechanism 33 repeatedly feedsfront wheel nuts 28 from the nut stock 30 onto the nut table 32, andarrays the front wheel nuts 28 on the nut table 32, and also feeds rearwheel nuts 28 from the nut stock 30 onto the nut table 32 and arrays therear wheel nuts 28 on the nut table 32.

Since the assembly line 12 includes the tire mounting apparatus 10disposed one on each side of the automobile body 14, the same operationsas described above are performed substantially simultaneously on eachside.

According to the first embodiment, the tire mounting apparatus 10includes the first working mechanism 20 and the second working mechanism22, which are separate from each other. The first working mechanism 20comprises the tire gripping means 42 and the temporary tightening means44, and the second working mechanism 22 comprises the full tighteningmeans 82.

Consequently, the first working mechanism 20 and the second workingmechanism 22 are effectively smaller and simpler than if only a singleworking mechanism were provided having a tire gripping means and atemporary tightening means.

In addition, the first working mechanism 20 may be constituted by asingle motor 64, due to the fact that the temporary tightening means 44is included therein. The motor 64 is much smaller and lighter than if atightening means were used to tighten the nuts both temporarily andfully, thereby easily allowing the first working mechanism 20 to be madesmaller and lighter overall.

Furthermore, the first working mechanism 20 and the second workingmechanism 22 share tire mounting operations. Therefore, a plurality ofoperation sequences can be performed concurrently, whereby the overalltire mounting control process can be made shorter and more efficient.

More specifically, as shown in FIG. 9, while the first working mechanism20 receives the nuts 28 and the tire W for the rear wheel, the secondworking mechanism 22 fully tightens the nuts 28 onto the hub bolts 18 inthe first mounting region 24 a on the front wheel side. Therefore,easily and reliably, the overall tire mounting process is made shorterand more efficient.

The tire mounting apparatus 10 also includes the third working mechanism33, which removes a certain number of (five or four) nuts 28 from thenut stock 30 and places the nuts 28 in an array on a nut table 32. Thefirst working mechanism 20 and the second working mechanism 22 do notcarry out the process of arraying the nuts 28, and thus the operationsequences thereof are made simpler and more efficient.

The feed path 16 intermittently feeds the automobile body 14 such thatthe first mounting region 24 a and the second mounting region 24 b ofthe automobile body 14 are positioned successively in the tire mountingstation. Therefore, the first working mechanism 20 and the secondworking mechanism 22 may be disposed one each in the tire mountingstation (on one of left and right sides) for dealing with the front andrear wheels of the automobile body 14.

When the number of bolts holes for the tire W is changed due to a changein the type of the automobile body 14, the tool unit 70 of the temporarytightening means 44 of the first working mechanism 20 also is changed.More specifically, the tool unit 70 with five nut runners 72 securedthereto is replaced with a new tool unit 70 having four nut runners 72mounted thereon.

In the second working mechanism 22, the cylinder 96 of the fulltightening means 82 is actuated to turn the interval adjuster 98 aboutthe support shaft 99 in order to adjust the interval (pitch). Theinterval between the first nut runner 90 and the second nut runner 94therefore is changed in pitch, depending on the arrangement of the fourhub bolts 18.

Second Embodiment

FIG. 10 is a perspective view of an assembly line 212 incorporating atire mounting apparatus 210 according to a second embodiment of thepresent invention.

The assembly line 212 has a feed path 216 for pitch-feeding anautomobile body (motor vehicle) 214 placed on a carriage 216 a to a tiremounting position. A pair of tire mounting apparatus 210 (only one ofwhich is shown in FIG. 1), disposed one on each side of the feed path216, automatically mount tires W onto hub bolts 218 of the automobilebody 214.

The tire mounting apparatus 210 includes a first working mechanism 220,a second working mechanism 222 a, and a third working mechanism 222 b,which are separate from each other and constructed depending on thedetails of working operations, to be described later.

The second working mechanism 222 a is disposed at a first mountingregion 224 a on a front wheel side of the automobile body 214, and thethird working mechanism 222 b is disposed at a second mounting region224 b on a rear wheel side of the automobile body 214. A tire chargingconveyor 226 on which tires W are placed is disposed near the firstworking mechanism 220.

Near the second working mechanism 222 a and the third working mechanism222 b, there are disposed nut stocks 230 a, 230 b accommodating thereinnuts 228 to be tightened on the hub bolts 118, and nut tables 232 a, 232b on which a certain number of (five or four) nuts 228 removed from thenut stocks 230 a are placed.

The first working mechanism 220 includes a robot body 234 having an arm236, which includes a hand 238 on a distal end with a rotatable indexbase 240 mounted thereon.

As shown in FIGS. 11 through 13, the index base 240 supports thereon atire gripping means 242 for gripping a tire W, and a temporarytightening means 244 for temporarily tightening nuts 228 on hub bolts218 with the tire W placed thereon.

The tire gripping means 242 has an attachment plate 246 secured to theindex base 240. As shown in FIGS. 11 and 12, a cam ring 250 is rotatablysupported on the attachment plate 246 by a plurality of guide rollers248. A plurality of (e.g., three) radially extending guide rails 252 aremounted on the attachment plate 246 at equal angular intervals.

Slide bases 254 are movably mounted on respective guide rails 252, andare coupled to the cam ring 250 by connecting rods 256. Tire holders 258are mounted on the slide bases 254. A cylinder 260 is swingably mountedon the attachment plate 246, and a rod 262 coupled to the cylinder 260is fixed to the cam ring 250.

As shown in FIG. 13, the temporary tightening means 244 is constitutedby a single motor 264 fixed to the attachment plate 246. The motor 264has a rotational drive shaft 264 a, to which there is secured a drivegear 266 held in mesh with a gear train 268. A tool unit 270 isdetachably mounted on the gear train 268.

The tool unit 270 includes five (or four) nut runners 272, which arerotatable in unison by the motor 264 through the gear train 268 and thedrive gear 266.

As shown in FIG. 10, the second working mechanism 222 a and the thirdworking mechanism 222 b, which are structurally identical to each other,include respective robot bodies 274 a, 274 b having arms 276 a, 276 b,each of which includes hands 278 a, 278 b on distal ends with indexbases 280 a, 280 b rotatably mounted thereon.

As shown in FIGS. 10 and 14, on the index base 280 a, there are mounteda first full tightening means 282 a for fully tightening nuts 228 thathave temporarily been tightened on hub bolts 218 in the first mountingregion 224 a, CCD image-capturing cameras (hereinafter referred tosimply as cameras) (first detection sensors) 284 a, 286 a for capturingimages of the first mounting region 224 a in order to detect thepositions of the respective hub bolts in the first mounting region 224a, and a nut chuck 287 a for removing a nut 228 from the nut stock 230 aand placing the nut 28 on the nut table 232 a.

On the index base 280 b, similarly, there are mounted a second fulltightening means 282 b for fully tightening nuts 228 that havetemporarily been tightened on hub bolts 218 in the second mountingregion 224 b, cameras (second detection sensors) 284 b, 286 b forcapturing images of the second mounting region 224 b, and a nut chuck287 b for removing a nut 228 from the nut stock 230 b and placing thenut 28 on the nut table 232 b.

The first full tightening means 282 a comprises a first nut runner 290coupled to a first motor 288, and a second nut runner 294 coupled to asecond motor 292. The first nut runner 290 and the second nut runner 294are variable by an interval adjuster 298 coupled to a rod 296 a thatextends from a pitch changing cylinder 296. The interval adjuster 298 isangularly movable about a support shaft 299. The first nut runner 290and the second nut runner 294 are capable of varying a pitch intervaldepending on whether five or four nuts are used to fasten the tire W.

The second full tightening means 282 b are identical in structure to thefirst full tightening means 282 a. Components thereof are denoted byidentical reference characters, and such features will not be describedin detail below.

As shown in FIG. 15, the cameras 284 a, 286 a of the second workingmechanism 222 a output image information concerning the first mountingregion 224 a to a first image processor 300, which processes the imageinformation. The cameras 284 b, 286 b of the third working mechanism 222b output image information concerning the second mounting region 224 bto a second image processor 302, which processes the image information.

Image information of a tire W placed on the tire charging conveyor 226is input from a camera (third detection sensor) 304 to the second imageprocessor 302, which processes the image information.

The first image processor 300 and the second image processor 302 areconnected to an arithmetic unit 306. The arithmetic unit 306 calculatesrelative positions of the hub bolts in the first mounting region 224 a,the hub bolts in the second mounting region 224 b, and bolt holes of atire W on the tire charging conveyor 226, and outputs the calculatedrelative positions to a main controller (control mechanism) 308. Basedon the processed image information input from the arithmetic unit 306,the main controller 308 controls operations of the first workingmechanism 220, and also controls operations of the second workingmechanism 222 a and the third working mechanism 222 b.

Operation of the tire mounting apparatus 210 thus constructed will bedescribed in relation to a mounting method according to the secondembodiment, with reference to the flowcharts shown in FIGS. 16 through18 and the timing chart shown in FIG. 19.

An operation sequence of the first working mechanism 220 is shown inFIG. 16, an operation sequence of the second working mechanism 222 a isshown in FIG. 17, and an operation sequence of the third workingmechanism 222 b is shown in FIG. 18. The first working mechanism 220,the second working mechanism 222 a, and the third working mechanism 222b operate in relation to each other, as shown in FIG. 19.

First, the operation sequence of the first working mechanism 220 will bedescribed below. After gripping five nuts 228 arrayed on the nut table232 a with five nut runners 272 of the temporary tightening means 244,the first working mechanism 220 grips a tire W on the tire chargingconveyor 226 with the tire gripping means 242 (step S41).

More specifically, as shown in FIG. 12, when the cylinder 260 isactuated to project the rod 262 in the direction indicated by the arrow,the cam ring 250 fixed to the rod 262 is rotated in the directionindicated by the arrow while being guided by the guide rollers 248. Theconnecting rods 256, the ends of which are coupled to the cam ring 250,move the respective slide bases 254 inwardly (toward the center) alongthe guide rails 252. Therefore, an outer circumferential surface of thetire W is pressed and held by the tire holders 258 mounted on the slidebases 254.

Having gripped the nuts 228 and the tire W, the first working mechanism220 moves toward the first mounting region 224 a under operation of therobot body 234 (step S42). If a front wheel corrective quantity, whichis produced based on images captured by the cameras 284 a, 286 aassociated with the second working mechanism 222 a, is input (step S43:YES), control proceeds to step S44, in which the tire W is set in thefirst mounting region 224 a.

Control then proceeds to step S45, in which the nuts 228 are temporarilytightened onto the respective hub bolts 218. More specifically, as shownin FIG. 13, the motor 264 is energized to cause the drive gear 266 andthe gear train 268 to rotate the nut runners 272 of the tool unit 270,thereby temporarily tightening the nuts 228 on the hub bolts 218.

When the tire W has been temporarily tightened as a front wheel in thefirst mounting region 224 a, a front wheel setting completion signal isoutput (step S46). Control then proceeds to step S47, in which the robotbody 234 moves away from the first mounting region 224 a toward the nuttable 232 b (step S47).

The nut runners 272 of the temporary tightening means 244 grip five nuts228 arrayed on the nut table 232 b, after which the robot body 234 isturned toward the tire charging conveyor 226. The tire gripping means242 grips a tire W (step S48), and then the tire gripping means 242 ismoved toward the second mounting region 224 b under actuation of therobot body 234 (step S49).

If a rear wheel corrective quantity, which is produced based on imagesignals from the cameras 284 b, 286 b associated with the third workingmechanism 222 b, is input (step S50: YES), as described later, controlproceeds to step S51, in which a rear wheel tire W is set in the secondmounting region 224 b.

After the nuts 228 have been temporarily tightened on the hub bolts 118in the second mounting region 224 b by the temporary tightening means244 (step S52), a rear wheel setting completion signal is output (stepS53). Thereafter, the first working mechanism 220 moves to the originalposition thereof (step S54), whereupon the process of temporarilytightening the tire on the automobile body 214 is finished.

Next, an operation sequence of the second working mechanism 222 a willbe described below with reference to FIG. 17.

After the robot body 274 a of the second working mechanism 222 a hasbeen operated in order to position the cameras 284 a, 286 a near thefirst mounting region 224 a, the cameras 284 a, 286 a read imageinformation of the front wheel hub bolts 218 in the first mountingregion 224 a (step S61).

Images read by the cameras 284 a, 286 a are output to the first imageprocessor 300, which calculates a corrective quantity for the hub bolts218 with respect to a reference position. The corrective quantity isoutput from the arithmetic unit 306 to the main controller 308 (stepS62).

The second working mechanism 222 a moves to a position out ofinterference with the operation sequence of the first working mechanism220 in the first mounting region 224 a (step S63). If a front wheelsetting completion signal is input from the first working mechanism 220(step S64: YES), then control proceeds to step S65, in which the secondworking mechanism 222 a moves to the first mounting region 224 a.

In the first mounting region 224 a, the five nuts 228 have already beentemporarily tightened onto the hub bolts 218. The first nut runner 290and the second nut runner 294 of the first full tightening means 282 aare rotated by the first motor 288 and the second motor 292 in order tofully tighten two of the nuts 228. Then, the first nut runner 290 andthe second nut runner 294 are turned a given angle. Thereafter, thefirst nut runner 290 and the second nut runner 294 fully tighten anothertwo of the temporarily tightened nuts 228. After the first nut runner290 and the second nut runner 294 are turned further, the first nutrunner 290, for example, fully tightens the remaining one of thetemporarily tightened nuts 228 (step S66).

After the tire W has been mounted in the first mounting region 224 a,the second working mechanism 222 a moves toward the nut stock 230 a. Thenut chuck 287 a of the second working mechanism 222 a removes five nuts228 from the nut stock 230 a, and places the five nuts 228 onto the nuttable 232 a (step S67). Control proceeds to step S68, in which thesecond working mechanism 22 moves to its original position, and performsthe same process as described above on a next automobile body 214.

An operation sequence of the third working mechanism 222 b will bedescribed below with reference to FIG. 18.

The robot body 274 b of the third working mechanism 222 b operates toposition the cameras 284 b, 286 b near the second mounting region 224 b,where the cameras 284 b, 286 b capture images of hub bolts 218 in thesecond mounting region 224 b (step S71). Images read by the cameras 284b, 286 b are output to the second image processor 302, which outputs acorrective quantity for the hub bolts 218 in the second mounting region224 b to the main controller 308 via the arithmetic unit 306 (step S72).

The third working mechanism 222 b moves to a position out ofinterference with the second mounting region 224 b (step S73). Controlthe proceeds to step S74, in which the nut chuck 287 b operates toremove five rear wheel nuts 228 from the nut stock 230 b and place therear wheel nuts 228 onto the nut table 232 a.

Thereafter, if a rear wheel setting completion signal is input from thefirst working mechanism 220 (step S75: YES), then control proceeds tostep S76, in which the second full tightening means 282 b of the thirdworking mechanism 222 b moves to the second mounting region 224 b. Uponrotation of the first nut runner 290 and the second nut runner 294, thesecond full tightening means 282 b fully tightens two nuts 228, two nuts228, and then one nut 228 (step S77). Thereafter, control proceeds tostep S78, in which the third working mechanism 222 b moves to itsoriginal position.

Since the assembly line 212 has the tire mounting apparatus 210 disposedone on each side of the automobile body 214, the same operations asdescribed above are performed substantially simultaneously on each side.

According to the second embodiment, the tire mounting apparatus 210includes the first working mechanism 220, the second working mechanism222 a, and the third working mechanism 222 b, which are separate fromeach other. The first working mechanism 220 comprises the tire grippingmeans 242 and the temporary tightening means 244, the second workingmechanism 222 a comprises the first full tightening means 282 a, and thethird working mechanism 222 b comprises the second full tightening means282 b.

Consequently, the first working mechanism 220, the second workingmechanism 222 a, and the third working mechanism 222 b are effectivelymade smaller and simpler than if only a single working mechanism wereprovided having a tire gripping means and a temporary tightening means.

In addition, the first working mechanism 220 may be constituted by thesingle motor 264, since the temporary tightening means 244 is includedtherein. The motor 264 therefore is much smaller and lighter than if atightening means were provided to tighten the nuts both temporarily andfully, thus easily allowing the first working mechanism 220 to be madesmaller and lighter.

Furthermore, the first working mechanism 220, the second workingmechanism 222 a, and the third working mechanism 222 b share the tiremounting operation. Therefore, a plurality of operation sequences can beperformed concurrently, whereby the overall tire mounting controlprocess is made shorter and more efficient.

More specifically, as shown in FIG. 19, while the first workingmechanism 220 receives the nuts 228 and the tire W for the front wheel,the third working mechanism 222 b moves the sensing cameras 284 b, 286 bto the second mounting region 224 b.

Operation of the second working mechanism 222 a to sense the firstmounting region 224 a, and operation of the third working mechanism 222b to sense the second mounting region 224 b are performedsimultaneously. The first working mechanism 220 does not need to performthe above sensing operation, and thus is able to temporarily tighten thetires W in the first mounting region 224 a and the second mountingregion 224 b more efficiently.

While the first working mechanism 220 mounts the nuts 228 and a tire Win the second mounting region 224 b, the second working mechanism 222 afully tightens the nuts 228 in the first mounting region 224 a, whilethe third working mechanism 222 b arrays nuts 228 on the nut table 232a. Therefore, easily and reliably, the tire mounting process can be madeshorter and more efficient overall.

When the number of bolt holes for the tire W is changed due to a changein the type of automobile body 214, the tool unit 270 of the temporarytightening means 244 of the first working mechanism 220 is changed. Morespecifically, the tool unit 270 having five nut runners 272 securedthereto is replaced with a new tool unit 270 having four nut runners 272mounted thereon.

In the second working mechanism 222 a and the third working mechanism222 b, the cylinders 296 of the first full tightening means 282 a andthe second full tightening means 282 b are actuated in order to turn theinterval adjusters 298 about the support shafts 299 so as to adjust theinterval (pitch) therebetween. The interval between the first nut runner290 and the second nut runner 294 thus is changed in pitch, depending onthe arrangement of the four hub bolts 218.

Third Embodiment

FIG. 20 is a perspective view of an assembly line 412 incorporating atire mounting apparatus 410 according to a third embodiment of thepresent invention.

The assembly line 412 has a feed path 416 for pitch-feeding anautomobile body (motor vehicle) 414 placed on a carriage 416 a to a tiremounting position. A pair of tire mounting apparatus 410 (only one isshown in FIG. 20), disposed one on each side of the feed path 416,automatically mount tires W onto hub bolts 418 of the automobile body414.

The tire mounting apparatus 410 has a tire setting robot 420, a nuttightening robot (second working mechanism) 422, and a balancermechanism (first working mechanism) 426 with a nut runner unit (workingunit) 424 mounted thereon.

The feed path 416 feeds the automobile body 414 intermittently so that afirst mounting region 428 a on a front wheel side of the automobile body414, and a second mounting region 428 b on a rear wheel side of theautomobile body 414 will be positioned successively in a tire mountingstation.

Near the tire setting robot 420, there is disposed a tire chargingconveyor 430 on which tires W are placed. Near the nut tightening robot422, there are disposed a nut stock 434 for accommodating nuts 432 to betightened on the hub bolts 418, and a nut arraying robot 438 forremoving a certain number of (five or four) nuts 432 from the nut stock434, and placing the nuts 432 in an array on a nut table 436.

The tire setting robot 420 includes a swingable robot body 440 having apair of arms 442, which include respective hands 444 on distal endsthereof, with tire grippers 446 mounted thereon. CCD image-capturingcameras (hereinafter simply referred to as cameras) 448 a, 448 b aremounted on the robot body 440, for capturing images of the firstmounting region 428 a and the second mounting region 428 b in order todetect positions of the respective hub bolts.

The nut tightening robot 422 includes a robot body 450 having an arm452, which includes a hand 454 on a distal end thereof. A gripper 456detachably coupled to the nut runner unit 424 is mounted on the hand454.

As shown in FIGS. 20 and 21, the nut runner unit 424 has a hollowcylindrical casing 458 housing five (or four) motors therein, not shown.Nut runners 460, which are coupled respectively to the motors, areexposed from an end of the hollow cylindrical casing 458. The nutrunners 460 are disposed in a circular pattern in alignment withrespective hub bolts 418 in the first mounting region 428 a and thesecond mounting region 428 b.

As shown in FIG. 21, the hollow cylindrical casing 458 has two threadedholes 458 a defined therein. The gripper 456 has holes 456 a definedtherein in alignment with the threaded holes 458 a. Screws 461 insertedthrough the holes 456 a are threaded into the threaded holes 458 a,thereby fastening the hollow cylindrical casing 458 to the gripper 456.

The balancer mechanism 426 comprises an air-operated floor-mountedbalancer. The balancer mechanism 426 includes an attachment 462 on whichthe nut runner unit 424 is mounted. The balancer mechanism 426 bears theweight of the nut runner unit 424, which is a heavy object, and also isable to hold the nut runner unit 424, which is movably mounted thereon.Alternatively, the balancer mechanism 426 may comprise aceiling-supported balancer.

The nut arraying robot 438 has an arm supporting on a distal end thereofa nut chuck 466, which is openable and closable for removing a nut 432accommodated in a nut stock 434, and placing the nut 432 on a nut table436.

As shown in FIG. 22, cameras 448 a, 448 b associated with the tiresetting robot 420 output image information concerning the first mountingregion 428 a and the second mounting region 428 b to an image processor470. The image processor 470 is connected to an arithmetic unit 472. Thearithmetic unit 472 calculates positions of the hub bolts in the firstmounting region 428 a as well as positions of the hub bolts in thesecond mounting region 428 b, and outputs the calculated positions to amain controller 474.

Based on the calculated information input from the arithmetic unit 472,the main controller 474 controls operations of the nut tightening robot422, and also controls operations of the tire setting robot 420 and thenut arraying robot 438.

Operation of the tire mounting apparatus 410 thus constructed will bedescribed in relation to a mounting method according to the thirdembodiment, with reference to the flowcharts shown in FIGS. 23 and 24and the timing chart shown in FIG. 25.

An operation sequence of the tire setting robot 420 is shown in FIG. 23,while an operation sequence of the nut tightening robot 422 is shown inFIG. 24. The tire setting robot 420 and the nut tightening robot 422operate in relation to each other, as shown in FIG. 25.

First, the operation sequence of the tire setting robot 420 will bedescribed below. The tire setting robot 420 grips a tire W disposed onthe tire charging conveyor 430 with the pair of tire grippers 446 (stepS81).

As the robot body 440 swings, the tire setting robot 420, which gripsthe tire W, moves the tire W gripped by the tire grippers 446 to amounting position (step S82). At this time, a first mounting region 428a on the front wheel side of the automobile body 414 is disposed in thetire mounting station (mounting position).

In the tire setting robot 420, the cameras 448 a, 448 b capture imagesof the first mounting region 428 a. The captured images are processed inorder to sense the hub bolts 418 (step S83).

Then, control proceeds to step S84, in which the tire setting robot 420sets a tire W in the first mounting region 428 a. A front wheel settingcompletion signal is output (step S85), and then it is determinedwhether or not the nut tightening robot 422 has completed tightening ofthe front wheel nuts 432 (step S86).

If a tightening completion signal for the nuts 432 is input (step S86:YES), then control proceeds to step S87, in which the tire setting robot420 moves toward a tire receiving position at the tire charging conveyor430. One of the rear wheel tires W that is placed on the tire chargingconveyor 430 is gripped by the tire grippers 446 of the tire settingrobot 420 (step S88).

The tire setting robot 420 moves toward the tire mounting position (stepS89). If the automobile body 414 is detected as having been fed a halfpitch (step S90: YES), i.e., if the second mounting region 428 b on therear wheel side is positioned in the tire mounting station, then controlproceeds to step S91, in which hub bolts 418 in the second mountingregion 428 b are sensed. The hub bolts 418 are sensed in the same mannerthat the front wheel hub bolts 418 were sensed in step S83.

Then, control proceeds to step S92, in which the tire W is set in thesecond mounting region 428 b. Then, a rear wheel tire setting completionsignal is output (step S93). In the second mounting region 428 b wherethe tire W has been set, nuts 432 are tightened onto the hub bolts 418.Once tightening of the nuts 432 is completed (step S94: YES), controlproceeds to step S95, in which the tire setting robot 420 moves to thetire receiving position.

An operation sequence of the nut tightening robot 422 will be describedbelow with reference to FIG. 24.

The nut tightening robot 422 is actuated to move the nut runner unit 424coupled to the gripper 456 toward the nut table 436. The nut runners 460of the nut runner unit 424 grip five front wheel nuts 432, which arearrayed on the nut table 436 (step S101).

Then, the nut tightening robot 422 is actuated in order to move the nutrunner unit 424 to a position near the first mounting region 428 a atthe mounting position (step S102). If the front wheel tire W is detectedas being set by the tire setting robot 420 (step S103: YES), thencontrol proceeds to step S104, in which the nut runners 460 of the nutrunner unit 424 are positioned in the first mounting region 428 a at therespective hub bolts 418.

The nut runners 460 then are rotated by respective motors, not shown, soas to tighten the nuts 432 on the respective hub bolts 418 (step S105).When tightening of the nuts 432 is completed, a nut tighteningcompletion signal is output (step S106).

The nut tightening robot 422 is actuated in order to move the nut runnerunit 424 toward a nut receiving position at the nut table 436 (stepS107), whereupon the nut runners 460 grip the rear wheel nuts 432 (stepS108).

After the automobile body 414 has been fed a half pitch, controlproceeds to step S109, in which the nut runner unit 424 is moved to aposition near the second mounting region 428 b at the mounting position.When it is judged that a rear wheel tire W has been set in the secondmounting region 428 b (step S110: YES), control then proceeds to stepS111, in which the nut runner unit 424 is positioned in the secondmounting region 428 b. The nut runners 460 are rotated in order totighten the nuts 432 on the hub bolts 418 in the second mounting region428 b (step S112).

At this time, tightening of the nuts 432 in the second mounting region428 b is completed (step S113). Control then proceeds to step S114, inwhich the nut runner unit 424 moves to the nut receiving position.

Since the assembly line 412 includes the tire mounting apparatus 410disposed one on each side of the automobile body 414, the sameoperations as those described above are performed substantiallysimultaneously on each side.

According to the third embodiment, the nut runner unit 424, which isconsiderably heavy, is mounted on the balancer mechanism 426. Therefore,the weight of the nut runner unit 424 is borne by the balancer mechanism426, and the nut runner unit 424 is capable of moving in variousdirections.

The nut tightening robot 422 is detachably coupled to the nut runnerunit 424, and is automatically operated according to a nut tighteningprocess, with the nut runner unit 424 being mounted on the balancermechanism 426.

Inasmuch as the balancer mechanism 426 bears the weight of the nutrunner unit 424, when the nut tightening robot 422 actually causes thenut runner unit 424 to operate, the load imposed on the nut tighteningrobot 422 by the nut runner unit 424 is effectively reduced. The nuttightening robot 422 can be reduced in size, thus easily making the tiremounting apparatus 410 smaller and simpler in its entirety.

When the nut tightening robot 422 is shut down for maintenance or thelike, the nut tightening robot 422 can be released from the nut runnerunit 424. The operator therefore is able to operate the nut runner unit424 easily while being assisted by the balancer mechanism 426.

Fourth Embodiment

FIG. 26 is a block diagram of an assembly line 482 incorporating a tiremounting apparatus 480 according to a fourth embodiment of the presentinvention. Those components of the assembly line 482 that are identicalto those of the assembly line 412 according to the third embodiment aredenoted by identical reference characters, and such features will not bedescribed in detail below.

The tire mounting apparatus 480 comprises a tire setting robot 420, anut tightening robot 422, and a balancer mechanism 484 having a nutrunner unit 424 mounted thereon. The balancer mechanism 484 comprises anelectrically operated balancer, which is controlled by a controller 488of a balancer controller 486.

The balancer controller 486 includes a force calculator 490 connected toa force sensor 492 mounted on the hand of the nut tightening robot 422.The force sensor 492 inputs a load, which is imposed on the hand of thenut tightening robot 422, to the force calculator 490.

According to the fourth embodiment, the nut runner unit 424 is operatedaccording to a nut tightening process performed by the nut tighteningrobot 422. When a relatively large reactive force is applied to the handof the nut tightening robot 422, the controller 488 controls an actuator(not shown) of the balancer mechanism 484 in order to reduce thereactive force to zero, or to a sufficiently small value, based on asignal that is input from the force sensor 492 to the force calculator490.

Therefore, the force required for the nut tightening robot 422 to feedthe nut runner unit 424 is significantly reduced, and hence the nuttightening robot 422 can reliably be made smaller in size.

Fifth Embodiment

FIG. 27 is a perspective view of an assembly line 502 incorporating atire mounting apparatus 500 according to a fifth embodiment of thepresent invention. Those components of the assembly line 502 that areidentical to those of the assembly line 412 according to the thirdembodiment are denoted by identical reference characters, and suchfeatures will not be described in detail below.

The tire mounting apparatus 500 comprises a tire setting robot 420, anut tightening robot (second working mechanism) 422, and a multijointrobot (first working mechanism) 504 having a nut runner unit (workingunit) 424 mounted thereon.

The multijoint robot 504 comprises a multijoint general-purpose robot,which is of the same structure as the nut tightening robot 422, forexample. The multijoint robot 504 has an arm 506 with a force sensor 508mounted on a distal end thereof. The force sensor 508 detects reactiveforces in directions of six axes, including an X-axis, a Y-axis, aZ-axis, an α1 axis, an α2 axis, and an α3 axis of a coordinate system,based on the force sensor 508. The multijoint robot 504 includesactuators 510 a through 510 d for actuating the joints thereof.

With the fifth embodiment thus constructed, when the nut tighteningrobot 422 operates the nut runner unit 424 according to a nut tighteningprocess, the force sensor 508 detects reactive forces along thedirections of the six axes.

The actuators 510 a through 510 d are controlled so as to reduce tozero, or to a sufficiently small value, the detected reactive forces.Therefore, the force required for the nut tightening robot 422 to feedthe nut runner unit 424 is significantly reduced, and hence the nuttightening robot 422 can reliably be made smaller in size.

In the third through fifth embodiments, the tire mounting apparatus 410,480, 500 have been described as constituting the working apparatus.However, the present invention is not limited to a tire mountingapparatus, but may also applied to various other types of workingapparatus.

Sixth Embodiment

FIG. 28 is a perspective view of an assembly line 610 incorporating apair of tire mounting apparatus 612 according to a sixth embodiment ofthe present invention.

The assembly line 610 comprises a tire mounting apparatus 612 and a feedpath 614. The feed path 614 pitch-feeds an automobile body (motorvehicle) 616, which is placed on a carriage 614 a, to a tire mountingposition. More specifically, the feed path 614 feeds the automobile body616 intermittently so that a first mounting region 618 a on a frontwheel side of the automobile body 616, and a second mounting region 618b on a rear wheel side of the automobile body 616 will be positionedsuccessively in the tire mounting station.

The tire mounting apparatus 612 (only one of which is shown in FIG. 28),disposed one on each side of the feed path 614, automatically mounttires W onto hub bolts 620 of the automobile body 616. The tire mountingapparatus 612 includes a first working mechanism 622, and a secondworking mechanism 624.

The first working mechanism 622 feeds a tire W carried by a tirecharging conveyor 626 to the first mounting region 618 a or the secondmounting region 618 b, and positions the tire W therein. The firstworking mechanism 622 is supplied with a plurality of nuts 630 from anut supply mechanism 628, and tightens the nuts 630 on the hub bolts 620with rotational drive power transmitted from the second workingmechanism 624.

The nut supply mechanism 628 comprises a nut stock 632 accommodatingnuts 630 therein, and a nut picking robot 636 for removing a certainnumber of (five or four) nuts 630 from the nut stock 632 and placing thenuts 630 in an array on a nut table 634. The nut picking robot 636 hasan arm that supports on a distal end a nut chuck 638, which is openableand closable for removing a nut 630 accommodated in the nut stock 632,and placing the nut 630 on the nut table 634.

As shown in FIG. 28, the first working mechanism 622 includes a robotbody 640, having an arm 642 that includes a hand 644 on a distal endwith a rotatable index base 646 mounted thereon. As shown in FIGS. 30and 31, the index base 646 includes a tire gripping mechanism 650 forgripping a tire W, a nut tightening mechanism 652 for tightening nuts630 onto the hub bolts 620 with the tire W disposed thereon, and lockmechanisms 654 (see FIG. 36) for attaching and detaching a nuttightening unit 722 a or a nut tightening unit 722 b, to be describedlater, of the nut tightening mechanism 652.

As shown in FIG. 28, two nut tightening unit stands 656 a, 656 b(hereinafter referred to as stands 656 a, 656 b) are disposed near thefirst working mechanism 622. Among the two stands 656 a, 656 b, thestand 656 b supports thereon a nut tightening unit 722 b, which differsfrom the nut tightening unit 722 a that is mounted on the index base646. The nut tightening unit 722 b differs from the nut tightening unit722 a as to the layout of the nut tighteners 726.

As shown in FIGS. 30 and 31, the tire gripping mechanism 650 includes alinear guide 660, which is actuatable by a motor, not shown. The linearguide 660 houses a non-illustrated drive shaft therein. When the driveshaft is rotated by the motor, two gripper arms 662 are displaced alongthe linear guide 660. The drive shaft includes threads thereon, whichare helically turned in opposite directions from the center of the driveshaft. Upon rotation of the drive shaft, the two gripper arms 662 aremoved in opposite directions while remaining in alignment with eachother. When the two gripper arms 662 are moved toward or away from eachother, the gripper arms 662 can grip or release a tire W therebetween.

Before describing the nut tightening mechanism 652 and the lockmechanisms 654 of the first working mechanism 622, the second workingmechanism 624 will first be described below.

As shown in FIG. 28, the second working mechanism 624 includes a robotbody 670, having an arm 672 that includes a hand 674 on a distal endwith a rotatable index base 676 mounted thereon. As shown in FIG. 32, onthe index base 676, there are mounted a rotational drive power generator678 for generating rotational drive power in order to tighten nuts 630onto the hub bolts 620 in the first mounting region 618 a and in thesecond mounting region 618 b, and CCD cameras 680, 682 (hereinafter alsoreferred to as “cameras 680, 682”) for capturing images of the firstmounting region 618 a and the second mounting region 618 b in order todetect positions of the hub bolts 620. The CCD cameras will hereinafterbe referred to simply as cameras.

The rotational drive power generator 678 comprises two motors 684 andtwo rotational drive power transmitters 686, which are coupled to themotors 684 for transmitting rotational drive power generated by themotors 684.

As shown in FIG. 33, each of the rotational drive power transmitters 686has a first rod 690, a first joint 692, a second rod 694, a second joint696, a tubular socket 698, and a helical spring 700.

The first rod 690 has one end coupled to the output shaft (not shown) ofthe motor 684, and another end coupled to the first joint 692. The firstjoint 692 is hollow in shape, and has a first hollow cylindrical portion702, a second hollow cylindrical portion 704 smaller in diameter thanthe first hollow cylindrical portion 702, and a first tapered portion706 interposed between the first hollow cylindrical portion 702 and thesecond hollow cylindrical portion 704. The first hollow cylindricalportion 702 has an internally threaded surface, which is held inthreaded engagement with an externally threaded end portion of the firstrod 690. The second joint 696 is identical in structure to the firstjoint 692, and has a third hollow cylindrical portion 708, a fourthhollow cylindrical portion 710 smaller in diameter than the third hollowcylindrical portion 708, and a second tapered portion 712 interposedbetween the third hollow cylindrical portion 708 and the fourth hollowcylindrical portion 710. The third hollow cylindrical portion 708 has aninternally threaded surface, which is held in threaded engagement withan externally threaded end portion of the tubular socket 698.

The second rod 694 has a cylindrical portion 714, together with a thirdtapered portion 716 and a fourth tapered portion 718, which are disposedon opposite ends of the cylindrical portion 714 and become progressivelygreater in diameter toward the ends thereof. The cylindrical portion 714of the second rod 694 has a diameter, which is slightly smaller than thediameter of the first hollow cylindrical portion 702 of the first joint692 and the fourth hollow cylindrical portion 710 of the second joint696. The third tapered portion 716 of the second rod 694 is housed inthe first joint 692 (first tapered portion 706), and is greater indiameter than the second hollow cylindrical portion 704. The fourthtapered portion 718 of the second rod 694 is housed in the second joint696 (second tapered portion 712), and is greater in diameter than thefourth hollow cylindrical portion 710. The helical spring 700 covers thesecond rod 694 and is interposed between the first joint 692 and thesecond joint 696.

Since the rotational drive power transmitters 686 are constructed asdescribed above, their rotational axes can be offset as shown in FIG.34. More specifically, when the rotational axis Y1 of the first joint692 and the rotational axis Y2 of the second joint 696 are offset fromeach other, rotational drive power can be transmitted from the firstjoint 692 to the second joint 696. The first joint 692, the second rod694, and the second joint 696 make up a universal joint mechanism.Accordingly, even when the nut tighteners 726 of the first workingmechanism 622 is changed in position, it is possible to transmitrotational drive power from the second working mechanism 624 to thefirst working mechanism 622.

The first working mechanism 622 will further be described below. Asshown in FIGS. 30 and 31, the nut tightening mechanism 652 comprises anattachment plate 720 fixed to the index base 646, and a nut tighteningunit 722 a detachably mounted on the attachment plate 720. The two lockmechanisms 654 referred to above are provided to secure the nuttightening unit 722 a to the attachment plate 720. According to thesixth embodiment, the nut tightening unit 722 a can be replaceddepending on the layout of the hub bolts 620 and the bolt holes Wa(i.e., the type of tire W). A nut tightening unit 722 b for replacementis disposed on the stand 656 b.

As shown in FIG. 29, the attachment plate 720 has a plurality of openingguides 724 to which the rotational drive power transmitters 686 of thesecond working mechanism 624 are coupled.

As shown in FIGS. 30 and 31, the nut tightening unit 722 a comprisesfive nut tighteners 726. The number of nut tighteners 726 is the same asthe number of hub bolts 620 and the number of bolt holes Wa.

As shown in FIG. 35, each of the nut tighteners 726 comprises a thirdrod 728, bearings 730, a wrench 732, and a helical spring 734.

The third rod 728 has an end 728 a disposed in one of the opening guides724 of the attachment plate 720 (see FIG. 36). The end 728 a is tapered.When the end 728 a is coupled to the tubular socket 698 of one of therotational drive power transmitters 686 of the second working mechanism624, rotational drive power can be transmitted from the second workingmechanism 624 to the third rod 728. As a result, the third rod 728 isrotated while being supported by the bearings 730. The third rod 728 hastwo cylindrical protrusions 736 through which rotational drive power istransmitted from the third rod 728 to the wrench 732.

The wrench 732 has holes 738 defined therein. The respective protrusions736 are received in the holes 738. The holes 738 extend in thelongitudinal direction (axial direction) of the nut tightening unit 722a, and have a width that is slightly larger than the diameter of theprotrusions 736. Therefore, the protrusions 736 can be displaced withinthe holes 738 along the axial direction of the nut tightening unit 722a. The wrench 732 has a recess 740 defined therein for receiving a nut630. The recess 740 is substantially equal in cross-sectional shape tothe nut 630. Therefore, when the recess 740 is rotated, the nut 630 thatis received therein also is rotated.

The helical spring 734 is interposed between the third rod 728 and thewrench 732. The third rod 728 is limited against displacement along theaxial direction of the nut tightening unit 722 a. However, the wrench732 can be displaced along the axial direction within a given range, inwhich the protrusions 736 are displaceable within the holes 738.Therefore, the helical spring 734 normally urges the wrench 732 to moveaway from the third rod 728. Upon rotation of the wrench 732, as the nut630 is tightened onto the hub bolt 620, the wrench 732 is displaced awayfrom the third rod 728. The nut 630 can therefore be tightened at adesired position on the hub bolt 620.

The lock mechanisms 654 and the stands 656 a, 656 b of the first workingmechanism 622 will be described below with reference to FIGS. 36 through39. As described above, the lock mechanisms 654 serve to secure the nuttightening unit 722 a to the attachment plate 720. When the nuttightening unit 722 a is unlocked from the attachment plate 720 throughoperation of the lock mechanisms 654, the nut tightening unit 722 a canbe detached from the attachment plate 720.

The lock mechanism 654 includes a stopper 742, a switching lever 744,and a link member 746 (only one lock mechanism 654 is shown in FIGS. 37Aand 37B). The stopper 742 can selectively press the nut tightening unit722 a. When the stopper 742 presses the nut tightening unit 722 a, thenut tightening unit 722 a is secured to the attachment plate 720. If thestopper 742 does not press the nut tightening unit 722 a, the nuttightening unit 722 a can be detached from the attachment plate 720. Theswitching lever 744 changes the pressed state of the stopper 742depending on the position thereof. The link member 746 cooperates withthe switching lever 744 in order to keep the nut tightening unit 722 apressed by the stopper 742, or to keep the nut tightening unit 722 areleased from the stopper 742.

More specifically, the switching lever 744 includes a roller 748disposed on one end, and a cam 750 disposed on the other end thereof.The switching lever 744 is bent at a substantially central region. Theswitching lever 744 is swingably supported by a first support shaft A1.The link member 746 has an end swingably supported on a second supportshaft A2 via the cam 750. A bent member 752, which supports the stopper742, is swingably supported on a third support shaft A3 on the other endof the link member 746. The bent member 752 also is swingably supportedon a fourth support shaft A4.

FIG. 38 shows in perspective the stand 656 a. The nut tightening unit722 a or 722 b is not held on the stand 656 a. As shown in FIG. 38, thestand 656 a comprises a base 756, a substantially U-shaped holder plate758, two positioning pins 760, two cylinders 762, substantially L-shapedengagement members 764 mounted respectively on distal ends of thecylinders 762 and having horizontal portions 764 a and vertical portions764 b, and first support members 766 affixed to second support members768, the engagement members 764 being swingably supported on the firstsupport members 766 for swinging movement about support shafts B1. Whenpressers 770 of the cylinders 762 are elevated, the horizontal portions764 a and the vertical portions 764 b are caused to swing about thesupport shafts B1.

A process of replacing the nut tightening units 722 a, 722 b (a processof placing the nut tightening unit 722 a on the stand 656 a) will bedescribed below with reference to FIG. 39. The nut tightening units 722a, 722 b are replaced when the type of the motor vehicle on which thetires W are to be mounted is changed, and hence, the layout of the hubbolts 620 and the bolt holes Wa (FIG. 28) also is changed.

For replacing the nut tightening unit 722 a with the nut tightening unit722 b, the nut tightening unit 722 a, which presently is mounted on thefirst working mechanism 622, is detached from the attachment plate 720and is placed on the stand 656 a. More specifically, the arm 642 of thefirst working mechanism 622 is displaced so as to position the nuttightening unit 722 a directly above the stand 656 a. Then, the nuttightening unit 722 a is vertically lowered until the positioning pins760 engage within positioning holes 772 defined in the nut tighteningunit 722 a. Consequently, the nut tightening unit 722 a is stabilized inposition.

When the rollers 748 of the lock mechanisms 654 abut against thehorizontal portions 764 a of the engagement members 764 of the stand 656a, the rollers 748 become displaced upwardly under the weight of the nuttightening mechanism 652 (see FIG. 37A). The stoppers 742 change fromthe pressing state to a releasing state, thereby allowing the nuttightening unit 722 a to become detached from the attachment plate 720.

When the arm 642 of the first working mechanism 622 is moved upwardly,the nut tightening unit 722 a remains placed on the stand 656 a, but thenut tightening unit 722 a is not mounted on the attachment plate 720.

Then, the arm 642 is moved to the stand 656 b on which the other nuttightening unit 722 b is placed, until the positioning pins 760 engagewith the attachment plate 720. When the attachment plate 720 abutsagainst the nut tightening unit 722 b, the cylinders 762 are actuated toturn the horizontal portions 764 a and vertical portions 764 b of theengagement members 764 about the support shafts B1. The verticalportions 764 b displace the rollers 748 downwardly, thereby causing thestoppers 742 to secure the nut tightening unit 722 b to the attachmentplate 720. A tire W then is installed using the new nut tightening unit722 b. As described above, the nut tightening unit 722 a and the nuttightening unit 722 b differ from each other as to the layout of the nuttighteners 726 thereof. More specifically, the circles formed by the nuttighteners 726 have different diameters. Alternatively, the nuttightening unit 722 a and the nut tightening unit 722 b may differ fromeach other as to the size of the nuts 630 that are held by the nuttighteners 726, or the number of nut tighteners 726.

FIG. 40 shows a control system of the tire mounting apparatus 612. Asshown in FIG. 40, cameras 680, 682 of the second working mechanism 624output image information of the first mounting region 618 a and thesecond mounting region 618 b to a first image processor 800.

The first image processor 800 also is supplied with image information ofa tire W (bolt holes Wa of the tire W) from a camera 802 (bolt holedetection sensor), which captures an image of the tire W placed on thetire charging conveyor 626.

A camera 804 for capturing an image of the nuts 630 arrayed on the nuttable 634 is fixedly positioned near the nut picking robot 636 of thenut supply mechanism 628. Image information of the nuts 630, which iscaptured by the camera 804, is input to a second image processor 806.

The first image processor 800 is connected to an arithmetic unit 808.The arithmetic unit 808 calculates relative positions of the hub bolts620 in the first mounting region 618 a, the hub bolts 620 in the secondmounting region 618 b, and bolt holes Wa of a tire W on the tirecharging conveyor 626. The arithmetic unit 808 then outputs thecalculated relative positions to a main controller (control mechanism)810. The second image processor 806 is connected to the arithmetic unit808 and processes the image information of the nuts 630, which iscaptured by the camera 804, and outputs the processed image informationto the main controller 810.

Based on the processed image information that is input from thearithmetic unit 808, the position information of the first workingmechanism 622 (position information of the arm 672, position informationof the gripper arms 662, etc.), and the position information of thesecond working mechanism 624 (position information of the arm 672,position information of the rotational drive power transmitters 686,etc.), the main controller 810 controls operation of the first workingmechanism 622, and also controls operation of the second workingmechanism 624 and the nut supply mechanism 628.

The tire mounting apparatus 612 according to the sixth embodiment isconstructed as described above. Operation of the tire mounting apparatus612 will be described with reference to the flowcharts shown in FIGS. 41and 42, and the timing chart shown in FIG. 43. FIG. 41 shows anoperation sequence primarily of the first working mechanism 622, andFIG. 42 shows an operation sequence primarily of the second workingmechanism 624. FIG. 43 shows the relationship between operationsequences of the first working mechanism 622, the second workingmechanism 624, and the nut supply mechanism 628.

First, the operation sequence primarily of the first working mechanism622 will be described below. In step S121 shown in FIG. 41, the firstworking mechanism 622 causes the five wrenches 732 to hold five nuts 630arrayed on the nut table 634.

Then, in step S122, the tire gripping mechanism 650 grips a tire W onthe tire charging conveyor 626. More specifically, while the tire W ispositioned between the two gripper arms 662 of the tire grippingmechanism 650, the linear guide 660 is actuated by the motor, not shown.The two gripper arms 662 are moved toward each other in order to grip anouter circumferential surface (ground contact surface) of the tire W.

When gripping the tire W, the two gripper arms 662 are positioned tohold positions (rotational phases) of the bolt holes Wa of the tire W inalignment with positions (rotational phases) of the nut tighteners 726of the nut tightening mechanism 652. As a result, the nuts 630 arepositioned in alignment with respective bolt holes Wa of the tire W.

For example, the above positioning process is performed as follows: Themain controller 810 detects positions of the bolt holes Wa of the tire Was well as positions of the nut tighteners 726. The main controller 810detects the positions of the bolt holes Wa based on image informationsupplied from the camera 802. The main controller 810 detects thepositions of the nut tighteners 726 based on the position of the twogripper arms 662 or the position of the index base 646, which supportsthe gripper arms 662, because the two gripper arms 662 and the nuttighteners 726 occupy fixed relative positions. Then, the index base 646is moved into a position where the positions of the bolt holes Wa andthe positions of the nut tighteners 726 are in alignment with eachother, thereby positioning the gripper arms 662. Since the grippingpositions of the gripper arms 662 and the bolt holes Wa of the tire Ware associated with each other, the positions of the bolt holes Wa canbe known by recognizing the positions of the gripper arms 662 and theposition of the index base 646.

In step S123, the first working mechanism 622, which has gripped thenuts 630 and the tire W, moves to a mounting ready position as the robotbody 640 is turned. At this time, the automobile body 616 has a firstmounting region 618 a on the front wheel side thereof positioned in thetire mounting station. In the tire mounting station, the two gripperarms 662 are vertically juxtaposed.

More specifically, based on the position information of the arm 642, andthe position information of the gripper arms 662, etc., the maincontroller 810 positions one of the gripper arms 662 such that thegripper arm 662 grips the tire W on an uppermost region of the tire W (aposition corresponding to a position Pu1 in FIG. 44), and positions theother gripper arm 662 such that the gripper arm 662 grips the tire W ona lowermost region of the tire W (a position corresponding to a positionP11 in FIG. 44).

With the first working mechanism 622 in the mounting ready position, thecameras 680, 682 of the second working mechanism 624 acquire imageinformation concerning the first mounting region 618 a (hereinafter alsoreferred to as “front wheel image information”). Based on the frontwheel image information, the first image processor 800 calculates acorrective quantity for the hub bolts 620 with respect to a referenceposition (step S124: YES). In step S125, the main controller 810calculates a quantity by which the gripper arms 662 that grip the tire Ware to be displaced (hereinafter referred to as an “arm displacementquantity”). The arm displacement quantity includes displacementquantities of the gripper arms 662 in an X-axis direction, a Y-axisdirection, and a Z-axis direction (see FIG. 28), as well as a rotationalangle of the tire W. The rotational angle of the tire W represents anangle through which the tire W is rotated by the gripper arms 662 inorder to bring positions (rotational phases) of the hub bolts 620 intoalignment with positions (rotational phases) of the bolt holes Wa whenthe center O of the tire W agrees with the center of the circlerepresented by the hub bolts 620 along the Y direction in FIG. 28. Therotational angle is calculated as an angle through which the tire W isrotated about the center O thereof.

According to the sixth embodiment, the main controller 810 limits therotational angle of the tire W to ±36° (see FIG. 44) for the followingreasons: The bolt holes Wa are positioned at equal angles along thecircle represented thereby. The bolt hole Wa, which is disposed in theuppermost position along the height of the motor vehicle (along the Zdirection in FIG. 28), resides in a range between certain positive andnegative angles on the circle from the uppermost position on the circle.Since the angle between two adjacent bolt holes Wa is calculated bydividing 360° by the number of bolt holes Wa, the positive and negativeangles referred to above are of positive and negative values, each ofwhich is produced by dividing the angle between adjacent two bolt holesWa by 2 (an angle produced by dividing 180° by the number of bolt holesWa). Since the number of bolt holes Wa is five in the sixth embodiment,the certain positive and negative angles referred to above are ±36°.Therefore, even if the rotational angle of the tire W is limited to ±36°at maximum, it is still possible to bring the positions (rotationalphases) of the hub bolts 620 and the bolt holes Wa into alignment witheach other.

In order to bring the positions (rotational phases) of the hub bolts 620and the bolt holes Wa into alignment with each other while also limitingthe rotational angle of the tire W to ±36°, the following process isperformed: Positions (rotational phases) of the hub bolts 620 aredetermined from the image information produced by the cameras 680, 682of the second working mechanism 624. For example, a hypothetical axis Z1is established, which extends from the center of the circle representedby the hub bolts 620 along the height direction (the Z direction shownin FIG. 28). Then, one of the five hub bolts 620, which is highest inposition, is detected, and the position (rotational phase) thereof isdetermined based on which side of the hypothetical axis Z1 the hub bolt620 is positioned, and the distance of the hub bolt 620 from thehypothetical axis Z1.

Positions (rotational phases) of the bolt holes Wa can be determinedfrom the relative positions of the gripper arms 662 and the bolt holesWa, as calculated in step S122.

In step S126, the main controller 810 displaces the gripper arms 662based on the arm displacement quantity calculated in step S125, therebypositioning the tire W in the first mounting region 618 a. Consequently,tire W is disposed in a position where the tire W waits for the nuts 630to be tightened.

According to the sixth embodiment, as described above, the gripper arms662 grip the uppermost and lowermost portions of the tire W, and therotational angle of the tire W is limited to ±36° in the mounting readyposition. As shown in FIG. 44, one of the gripper arms 662, which gripsan upper portion of the tire W, grips a portion of the ground contactsurface of the tire W that has a symmetric axis represented by ahypothetical axis Z2 (which is aligned with the hypothetical axis Z1)extending through the center O of the tire W and the uppermost regionPut, and which corresponds to a first central angle β1 of 72°.Similarly, one of the gripper arms 662, which grips a lower portion ofthe tire W, grips a portion of the ground contact surface of the tire Wthat has a symmetric axis represented by the hypothetical axis Z2, andwhich corresponds to a second central angle β2 of 72°. Stated otherwise,in the sixth embodiment, the ranges of the ground contact surfaces thatcan be gripped by the gripper arms 662 represent the upper and lowerportions of the tire W, whereas the rotational angle of the tire W islimited to ±36°.

The gripper arm 662, which grips the upper portion of the tire W, isdisplaced in a clearance 822 between a fender 820 of the automobile body616 and the tire W.

In order to limit the positions where the gripper arms 662 grip the tireW to within the above range, the gripper arms 662 may not grip theuppermost and lowermost portions of the tire W in the mounting readyposition. When the tire W is positioned with respect to the automobilebody 616, the tire W may be rotated in order to limit positions wherethe gripper arms 662 grip the tire W so as to lie within the aboverange.

The above limitation on the gripping positions is not effective if thenumber of bolt holes Wa or hub bolts 620 is small (specifically, 3 orsmaller). The above limitation should preferably be imposed only if thenumber of bolt holes Wa or hub bolts 620 is 4 or greater.

When positioning of the tire W has been completed, in step S127, themain controller 830 couples the second working mechanism 624 to thefirst working mechanism 622. More specifically, the main controller 830brings the tubular sockets 698 of the rotational drive power generator678 of the second working mechanism 624 into engagement with third rods728 of the nut tightening mechanism 652 of the first working mechanism622. In step S128, the second working mechanism 624 transmits rotationaldrive power to the first working mechanism 622 in order to tighten thenuts 630 onto the hub bolts 620. More specifically, the rotational drivepower generator 678 transmits rotational drive power to the nuttightening mechanism 652. The wrenches 732 of the first workingmechanism 622 are rotated in order to tighten the nuts 630 held by thewrenches 732 on the hub bolts 620. While the nuts 630 are tightened, thegripper arms 662 are fixed in position and kept within the above limitedrange.

After the tire W has been mounted as a front wheel in the first mountingregion 618 a, the second working mechanism 624 is moved out ofinterference (step S129: YES). In step S130, the robot body 640 of thefirst working mechanism 622 is moved away from the first mounting region618 a toward its original position near the nut table 634.

The above process performed in the first mounting region 618 a also isperformed in the second mounting region 618 b. In other words, stepsS131 through S140, which are similar to steps S121 through S130, areperformed for the second mounting region 618 b. In steps S130 throughS134, as shown in FIG. 28, the automobile body 616 is intermittently fedalong the feed path 614 in the X direction. The second mounting region618 b on the rear wheel side of the automobile body 616 is nowpositioned in the tire mounting station.

After mounting of the tire W in the second mounting region 618 b hasbeen completed, the same process described above will be performed onanother automobile body 616.

The operation sequence primarily of the second working mechanism 624will be described below with reference to FIG. 42.

The robot body 670 of the second working mechanism 624 is operated inorder to position the cameras 680, 682 in the tire mounting station.When the first mounting region 618 a on the front wheel side of theautomobile body 616 is placed in the tire mounting station (step S151:YES), in step S152, the cameras 680, 682 read image information of frontwheel hub bolts 620 in the first mounting region 618 a.

In step S153, image information read by the cameras 680, 682 is outputto the first image processor 800, which calculates a corrective quantityfor the hub bolts 620 with respect to a reference position. For example,a hypothetical axis Z1 extending from the center of the circlerepresented by five hub bolts 620 along the height of the automobilebody 616 may be assumed, and one of the five hub bolts 620, which is thehighest in position on the hypothetical axis Z1, may be regarded as areference position. The corrective quantity is output from thearithmetic unit 808 to the main controller 810.

In step S154, the second working mechanism 624 moves to a position outof interference with the operation sequence of the first workingmechanism 622 in the first mounting region 618 a. If positioning of thetire W by the first working mechanism 622 has been completed (step S155:YES), then in step S156, the second working mechanism 624 is coupled tothe first working mechanism 622. More specifically, the rotational drivepower transmitters 686 of the second working mechanism 624 are coupledto nut tighteners 726 of the first working mechanism 622.

In step S157, the motor 684 of the second working mechanism 624generates rotational drive power, which is transmitted via therotational drive power transmitters 686 to the nut tighteners 726. Thenuts 630 are tightened onto the hub bolts 620, thereby mounting the tireW in the first mounting region 618 a. While the number of rotationaldrive power transmitters 686 is 2, the number of nut tighteners 726 is5. Therefore, the rotational drive power transmitters 686 are coupled tothe nut tighteners 726 a plurality of times (i.e., two nuts 630, twonuts 630, and one nut 630 are successively tightened onto the hub bolts620).

After the tire W has been mounted in the first mounting region 618 a, instep S158, the second working mechanism 624 moves out of interference.In step S159, the second working mechanism 624 moves to a rear wheel hubbolt detecting position. In step S160, the second working mechanism 624detects whether or not the automobile body 616 has been fed a half pitchalong the feed path 614.

If it is judged that the automobile body 616 has been fed a half pitch(step S160: YES), i.e., if it is judged that the second mounting region618 b on the rear wheel side has been placed in the tire mountingstation, then steps S161 through S167, which are the same as steps S152through S158, are executed for the second mounting region 618 b. In stepS168, the second working mechanism 624 moves to a front hub boltposition.

After mounting of a tire W in the second mounting region 618 b has beencompleted, the same process as described above will be performed onanother automobile body 616.

As shown in FIG. 43, using the nut chuck 638, the nut supply mechanism628 repeats the process of feeding front wheel nuts 630 from the nutstock 632 to the nut table 634 and arraying the front wheel nuts 630 onthe nut table 634, and also repeats the process of feeding rear wheelnuts 630 from the nut stock 632 to the nut table 634 and arraying therear wheel nuts 630 on the nut table 634.

Since the assembly line 610 includes the tire mounting apparatus 612,disposed one on each side of the automobile body 616, the sameoperations described above are performed substantially simultaneously oneach side.

The nut tightening unit 722 a or 722 b is replaced depending on thepositions of the hub bolts 620 and the bolt holes Wa. For example, themain controller 810 determines whether, based on the image informationproduced by the first image processor 600, the positions of the boltholes Wa are different from the position of the nut tightening unit 722a or 722 b currently in use. If the positions are different, the maincontroller 810 may replace one of the nut tightening units 722 a, 722 bwith the other.

According to the sixth embodiment, as described above, in the tirepositioning process (S126, S166 in FIG. 41) and the nut tighteningprocess (S128, S138 in FIGS. 41 and 5157, S166 in FIG. 42), thepositions where the pair of gripper arms 662 grip the tire W are limitedto upper and lower portions of the tire W. Consequently, a tire W canrelatively easily be installed on the automobile body 616, even if theclearance 822 between the tire W and the fender 820 is small.

More specifically, when the tire W is not in contact with the ground,the tire W, the first mounting region 618 a, and the second mountingregion 618 b are biased by suspensions, not shown, and are positionedlower than when the tire W is in contact with the ground, because thetire W is not subject to reactive forces from the ground. Therefore,before the tire W is mounted, the clearance 822 between the firstmounting region 618 a and the second mounting region 618 b (particularlyupper portions thereof) and the fender 820 is greater than the clearance822 after the tire W is mounted and held in contact with the ground.According to the sixth embodiment, during the process of positioning atire in a tire mounting region (tire positioning process) and theprocess of tightening nuts 630 on the hub bolts 620 (nut tighteningprocess), positions where the pair of gripper arms 662 grip the tire Ware limited to upper and lower portions of the tire W. When the tire Wis in contact with the ground, even if the clearances between left,right, and upper portions of the tire W and the fender 820 are small,thus making it difficult for the tire W to be gripped with either of thegripper arms 662, it is still possible to grip the tire W in theclearance 822, and hence the tire W can be mounted on the motor vehiclerelatively easily.

According to the sixth embodiment, the rotational axis Y1, along whichrotational drive power for tightening the nuts 630 is transmitted, isoffset from the rotational axis Y2. Therefore, it is possible totransmit rotational drive power to the nut tighteners 726 of the nuttightening units 722 a, 722 b, where the nut tighteners 726 arepositioned in different layouts. Rotational drive power, which is neededto tighten the nuts 630 with the nut tightening units 722 a, 722 b, canthus be supplied from the single rotational drive power generator 678.Stated otherwise, even though a plurality of rotational drive powergenerators 678 are not provided, tires W can still be mounted on aplurality of automobile bodies 616 in which hub bolts 620 and bolt holesWa have different layouts, by replacing one of the nut tightening units722 a, 722 b with the other. Accordingly, the tire mounting apparatuscan be reduced in size and cost overall.

The third rods 728 of the first working mechanism 622 have tapered ends728 a, and the rotational drive power transmitters 686 of the secondworking mechanism 624 have the tubular sockets 698. When the ends 728 aengage in the tubular sockets 698, rotational drive power can betransmitted therebetween. Even if the rotational axis Y1 of therotational drive power transmitters 686 and the rotational axis Y2 ofthe third rods 728 become offset from each other, the tubular sockets698 of the second working mechanism 624 and the third rods 728 of thefirst working mechanism 622 engage with each other, thus making itpossible to transmit rotational drive power.

According to the sixth embodiment, furthermore, the first workingmechanism 622 grips a tire W and tightens nuts 630. The second workingmechanism 624 generates rotational drive power for tightening the nuts630, and transmits rotational drive power to the nut tighteningmechanism 652 of the first working mechanism 622 in order to tighten thenuts 630. Consequently, the first working mechanism 622 and the secondworking mechanism 624 are effectively made smaller and simpler than ifthe tire W were gripped and the nuts 630 were tightened only by a singleworking mechanism. Since the tire W is gripped and the nuts 630 aretightened by a single working mechanism (the first working mechanism622), the tire W and the nuts 630 are less likely to change theirrelative positions, thus making it possible to easily identify positionswhere the nuts 630 are to be tightened.

The first working mechanism 622 places a plurality of nuts 630 inassociation with respective hub bolts 620, and performs the nuttightening process (S128, S138 in FIG. 41, and S157, S166 in FIG. 42)while the tire gripping mechanism 650 is fixed in position. In the nuttightening process, therefore, it is possible to keep the first workingmechanism 622 in a constant attitude, and to control the first workingmechanism 622 with ease.

The second working mechanism 624 includes the rotational drive powertransmitters 686 (tubular sockets 698) for transmitting rotational drivepower. The nut tightening mechanism 652 of the first working mechanism622 includes the third rod 728, the bearings 730, the wrench 732, andthe helical spring 734, for each of the hub bolts 620. Thus, it is easyto tighten the nuts 630 with the nut tightening mechanism 652 while thetire W is fixed in position by the tire gripping mechanism 650.

The present invention is not limited to the above embodiments, but mayincorporate and employ various additional structural details based onthe content of the above description.

The invention claimed is:
 1. A tire mounting apparatus for automaticallymounting a tire onto hub bolts of a motor vehicle, comprising: a firstworking mechanism including tire gripping means for gripping the tire,and temporary tightening means for temporarily tightening nuts on thehub bolts on which the tire has been placed; and a separate secondworking mechanism including full tightening means for fully tighteningthe nuts that have been temporarily tightened by the first workingmechanism, wherein the tire mounting apparatus feeds and positions themotor vehicle intermittently with respect to the first and secondworking mechanisms in a tire mounting station, so that the first workingmechanisms temporarily tightens the nuts on the hub bolts on a frontwheel side and on a rear wheel side of the motor vehicle successively asthe motor vehicle is intermittently fed and positioned, and the secondworking mechanism fully tightens the temporarily tightened nutssuccessively on the front wheel side and on the rear wheel sidesuccessively as the motor vehicle is intermittently fed and positionedafter the temporary tightening, and wherein only the first workingmechanism includes the tire gripping means.
 2. The tire mountingapparatus according to claim 1, wherein the second working mechanismincludes a detection sensor for detecting positions of the hub bolts ofthe motor vehicle.
 3. The tire mounting apparatus according to claim 1,further comprising: a bolt hole detection sensor for detecting boltholes of the tire, which is disposed in a tire supply; and a controlmechanism for processing hub bolt position information of the motorvehicle and bolt hole position information of the tire, and controllingoperation of the first working mechanism.
 4. The tire mounting apparatusaccording to claim 1, wherein the temporary tightening means comprises:a plurality of detachable nut runners; and a single rotational drivesource for rotating the nut runners in unison with each other.
 5. Thetire mounting apparatus according to claim 1, wherein the fulltightening means comprises: two nut runners; and an interval adjusterfor adjusting an interval between the two nut runners.
 6. The tiremounting apparatus according to claim 1, further comprising: a thirdworking mechanism for arraying the nuts in relation to the temporarytightening means.